Sharad Jaiswal

Sharad Jaiswal

1548664311

100+ PHP Interview Questions - Interview Questions On PHP 2019 - Online...

With the modernization of the world, everyone is trying to seek knowledge in the field of digital marketing to place his or her steps with the world. In today’s technology-driven world, organizations have achieved digital benefits to increase their demand and profit. But, to achieve this goal, it is quite important to make the sites user-friendly and highly-interactive. For this, only PHP language can fulfill these objectives. Go for PHP without any fear and become the mastermind in that field. If you are PHP lover, then you are in the right place. Read the full article if you want to know about the scope and career in the PHP language.

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Top 130 Android Interview Questions - Crack Technical Interview Now!

Android Interview Questions and Answers from Beginner to Advanced level

DataFlair is committed to provide you all the resources to make you an android professional. We started with android tutorials along with practicals, then we published Real-time android projects along with source code. Now, we come up with frequently asked android interview questions, which will help you in showing expertise in your next interview.

android interview questions

Android Interview Questions – Get ready for your next interview

Android – one of the hottest technologies, which is having a bright future. Get ready to crack your next interview with the following android interview questions. These interview questions start with basic and cover deep concepts along with advanced topics.

Android Interview Questions for Freshers

1. What is Android?

Android is an open-source mobile operating system that is based on the modified versions of Linux kernel. Though it was mainly designed for smartphones, now it is being used for Tablets, Televisions, Smartwatches, and other Android wearables.

2. Who is the inventor of Android Technology?

The inventors of Android Technology are- Andry Rubin, Nick Sears, and Rich Miner.

3. What is the latest version of Android?

The latest version of Android is Android 10.0, known as Android Q. The upcoming major Android release is Android 11, which is the 18th version of Android. [Note: Keep checking the versions, it is as of June 2020.]

4. How many Android versions can you recall right now?

Till now, there are 17 versions of Android, which have their names in alphabetical order. The 18th version of Android is also going to come later this year. The versions of Android are here:

  • Android 1.0 – Its release is 23 September 2008.
  • Android 1.1 – Its release date is 9 February 2009.
  • Android 1.5 – Its name is Cupcake, Released on 27 April 2009.
  • Android 1.6 – Its name is Donut, Released on 15 September 2009.
  • Android 2.0 – Its name is Eclair, Released on 26 October 2009
  • Android 2.2 – Its name is Froyo, Released on 20 May 2010.
  • Android 2.3 – Its name is Gingerbread, Released on 06 December 2010.
  • Android 3.0 – Its name is Honeycomb, Released on 22 February 2011.
  • Android 4.0 – Its name is Ice Cream Sandwich, Released on 18 October 2011.
  • Android 4.1 – Its name is Jelly Bean, Released on 9 July 2012.
  • Android 4.4 – Its name is KitKat, Released on 31 October 2013.
  • Android 5.0 – Its name is Lollipop, Released on 12 November 2014.
  • Android 6.0 – Its name is Marshmallow, Released on 5 October 2015.
  • Android 7.0 – Its name is Nougat, Released on 22 August 2016.
  • Android 8.0 – Its name is Oreo, Released on 21 August 2017.
  • Android 9.0 – Its name is Pie, Released on 6 August 2018.
  • Android 10.0 – Its name is Android Q, Released on 3 September 2019.
  • Android 11.0 – As of now, it is Android 11.

5. Explain the Android Architecture with its components.

This is a popular android developer interview question

Android Architecture consists of 5 components that are-

a. Linux Kernel: It is the foundation of the Android Architecture that resides at the lowest level. It provides the level of abstraction for hardware devices and upper layer components. Linux Kernel also provides various important hardware drivers that act as software interfaces for hardwares like camera, bluetooth, etc.

b. Native Libraries: These are the libraries for Android that are written in C/C++. These libraries are useful to build many core services like ART and HAL. It provides support for core features.

c. Android Runtime: It is an Android Runtime Environment. Android Operating System uses it during the execution of the app. It performs the translation of the application bytecode into the native instructions. The runtime environment of the device then executes these native instructions.

d. Application Framework: Application Framework provides many java classes and interfaces for app development. And it also provides various high-level services. This complete Application framework makes use of Java.

e. Applications: This is the topmost layer of Android Architecture. It provides applications for the end-user, so they can use the android device and compute the tasks.

6. What are the services that the Application framework provides?

The Android application framework has the following key services-

a. Activity Manager: It uses testing and debugging methods.

b. Content provider: It provides the data from application to other layers.

c. Resource Manager: This provides users access to resources.

d. Notification Manager: This gives notification to the users regarding actions taking place in the background.

e. View System: It is the base class for widgets, and it is also responsible for event handling.

7. What are the important features of Linux Kernel?

The important features of the Linux Kernel are as follows:

a. Power Management: Linux Kernel does power management to enhance and improve the battery life of the device.

b. Memory Management: It is useful for the maximum utilization of the available memory of the device.

c. Device Management: It includes managing all the hardware device drivers. It maximizes the utilization of the available resources.

d. Security: It ensures that no application has any such permission that it affects any other application in order to maintain security.

e. Multi-tasking: Multi-tasking provides the users the ease of doing multiple tasks at the same time.

8. What are the building blocks of an Android Application?

This is a popular android interview question for freshers.

The main components of any Android application are- Activity, Services, Content Provider, and Broadcast Receiver. You can understand them as follows:

a. Activity- It is a class that acts as the entry point representing a single screen to the user. It is like a window to show the user interface.

b. Services- Services are the longest-running component that runs in the background.

c. Content Provider- The content provider is an essential component that allows apps to share data between themselves.

d. Broadcast receivers- Broadcast receiver is another most crucial application component. It helps the apps to receive and respond to broadcast messages from the system or some other application.

9. What are the important components of Android Application?

The Components of Android application are listed below:

  1. Widgets
  2. Intents
  3. Views
  4. Notification
  5. Fragments
  6. Layout XML files
  7. Resources

10. What are the widgets?

Widgets are the variations of Broadcast receivers. They are an important part of home screen customization. They often display some data and also allow users to perform actions on them. Mostly they display the app icon on the screen.

11. Can you name some types of widgets?

Mentioned below are the types of widgets-

a. Informative Widgets: These widgets show some important information. Like, the clock widget or a weather widget.

b. Collective Widgets: They are the collection of some types of elements. For example, a music widget that lets us change, skip, or forward the song.

c. Control Widgets: These widgets help us control the actions within the application through it. Like an email widget that helps check the recent mails.

d. Hybrid Widgets: Hybrid widgets are those that consist of at least two or more types of widgets.

12. What are Intents?

Intents are an important part of Android Applications. They enable communication between components of the same application as well as separate applications. The Intent signals the Android system about a certain event that has occurred.

13. Explain the types of intents briefly?

Intent is of three types that are-

a. Implicit Intents: Implicit intents are those in which there is no description of the component name but only the action.

b. Explicit Intents: In explicit intents, the target component is present by declaring the name of the component.

c. Pending Intents: These are those intents that act as a shield over the Intent objects. It covers the intent objects and grants permission to the external app components to access them.

14. What is a View?

A view is an important building block that helps in designing the user interface of the application. It can be a rectangular box or a circular shape, for example, Text View, Edit Text, Buttons, etc. Views occupy a certain area of the screen, and it is also responsible for event handling. A view is the superclass of all the graphical user interface components.

15. What do you understand by View Group?

It is the subclass of the ViewClass. It gives an invisible container to hold layouts or views. You can understand view groups as special views that are capable of holding other views, that are Child View.

16. What do you understand about Shared Preferences?

It is a simple mechanism for data storage in Android. In this, there is no need to create files, and using APIs, it stores the data in XML files. It stores the data in the pair of key-values. SharedPreferences class lets the user save the values and retrieve them when required. Using SharedPreferences we can save primitive data like- boolean, float, integer, string and long.

17. What is a Notification?

A notification is just like a message that shows up outside the Application UI to provide reminders to the users. They remind the user about a message received, or some other timely information from the app.

18. Give names of Notification types.

There are three types of notifications namely-

a. Toast Notification- This notification is the one that fades away sometime after it pops up.

b. Status Notification- This notification stays till the user takes some action on it.

c. Dialog Notification- This notification is the result of an Active Activity.

19. What are fragments?

A fragment is a part of the complete user interface. These are present in Activity, and an activity can have one or more fragments at the same time. We can reuse a fragment in multiple activities as well.

20. What are the types of fragments?

There are three types of fragments that are: Single Fragment, List Fragment, Fragment Transactions.

  1. Single Transactions can only show a single view for the user.
  2. List Fragments have a special list view feature that provides a list from which the user can select one.
  3. Fragment Transactions are helpful for the transition between one fragment to the other.

Frequently asked Android Interview Questions and Answers

21. What are Layout XML files?

Layout XML files contain the structure for the user interface of the application. The XML file also contains various different layouts and views, and they also specify various GUI components that are there in Activity or fragments.

22. What are Resources in Android Application?

The resources in Android Apps defines images, texts, strings, colors, etc. Everything in resources directory is referenced in the source code of the app so that we can use them.

23. Can you develop Android Apps with languages other than Java? If so, name some.

Yes, there are many languages that we can work with, for the development of Android Applications. To name some, I would say Java, Python, C, C++, Kotlin, C#, Corona/LUA.

24. What are the states of the Activity Lifecycle?

Activity lifecycle has the following four stages-

a. Running State: As soon as the activity starts, it is the first state.

b. Paused State: When some other activity starts without closing the previous one, the running activity turns into the Paused state.

c. Resume State: When the activity opens again after being in pause state, it comes into the Resume State.

d. Stopped State: When the user closes the application or stops using it, the activity goes to the Stopped state.

25. What are some methods of Activity?

The methods of Activity are as follows:

  • onCreate()
  • onStart()
  • onPause()
  • onRestart()
  • onResume()
  • onStop()
  • onDestroy()

26. How can you launch an activity in Android?

We launch an activity using Intents. For this we need to use intent as follows:

  1. ntent intent_name= new Intent(this, Activity_name.class);
  2. startActivity(intent_name);

27. What is the service lifecycle?

There are two states of a service that are-

a. Started State: This is when the service starts its execution. A Services come in start state only through the startService() method.

b. Bounded State: A service is in the bounded state when it calls the method bindService().

28. What are some methods of Services?

The methods of service are as follows-

  • onStartCommand()
  • onBind()
  • onCreate()
  • onUnbind()
  • onDestroy()
  • onRebind()

29. What are the types of Broadcast?

Broadcasts are of two types that are-

a. Ordered Broadcast: Ordered broadcasts are Synchronous and work in a proper order. It decides the order by using the priority assigned to the broadcasts.

b. Normal Broadcast: These are asynchronous and unordered. They are more efficient as they run unorderly and all at once. But, they lack full utilization of the results.

30. What are useful impotent folders in Android?

The impotent folders in an Android application are-

  1. build.xml- It is responsible for the build of Android applications.
  2. bin/ – The bin folder works as a staging area to wrap the files packages into the APK.
  3. src/ – The src is a folder where all the source files of the project are present.
  4. res/ – The res is the resource folder that stores values of the resources that are used in the application. These resources can be colors, styles, strings, dimensions, etc.
  5. assets/ – It provides a facility to include files like text, XML, fonts, music, and video in the Android application.

31. What are the important files for Android Application when working on Android Studio?

This is an important android studio interview question

There are following three files that we need to work on for an application to work-

a. The AndroidManifest.xml file: It has all the information about the application.

b. The MainActivity.java file: It is the app file that actually gets converted to the dalvik executable and runs the application. It is written in java.

c. The Activity_main.xml file: It is the layout file that is available in the res/layout directory. It is another mostly used file while developing the application.

32. Which database do you use for Android Application development?

The database that we use for Android Applications is SQLite. It is because SQLite is lightweight and specially developed for Android Apps. SQLite works the same way as SQL using the same commands.

33. Tell us some features of Android OS.

The best features of Android include-

  1. Multi-tasking
  2. Support for a great range of languages
  3. Support for split-screen
  4. High connectivity with 5G support
  5. Motion Control

34. Why did you learn Android development?

Learning Android Studio is a good idea because of the following-

  1. It has a low application development cost.
  2. It is an open-source platform.
  3. It has multi-platform support as well as Multi-carrier support.
  4. It is open for customizations.
  5. Android is a largely used operating system throughout the world.

35. What are the different ways of storage supported in Android?

The various storage ways supported in Android are as follows:

  1. Shared Preference
  2. Internal Storage
  3. External Storage
  4. SQLite Databases
  5. Network Connection

36. What are layouts?

Layout is nothing but arrangements of elements on the device screen. These elements can be images, tests, videos, anything. They basically define the structure of the Android user interface to make it user friendly.

37. How many layout types are there?

The type of layouts used in Android Apps are as follows:

  1. Linear Layout
  2. Relative Layout
  3. Constraint Layout
  4. Table Layout
  5. Frame Layout
  6. Absolute Layout
  7. Scrollview layout

38. What is an APK?

An APK stands for Android Package that is a file format of Android Applications. Android OS uses this package for the distribution and installation of the Android Application.

39. What is an Android Manifest file?

The manifest file describes all the essential information about the project application for build tools, Android operating system, and google play. This file is a must for every Android project that we develop, and it is present in the root of the project source set.

#android tutorials #android basic interview questions #android basic questions #android developer interview questions #android interview question and answer #android interview questions #android interview questions for experienced #android interview questions for fresher

Biju Augustian

Biju Augustian

1575031899

PHP Interview Questions with Solutions: Prepare for PHP Interview

Description
In this course you will be introduced with some tricky questions that everyone face during their interview. In each solutions I have included some useful functions which we generally use at the time of development also. I have covered the following area in my course with Questions, Attractive Presentations and Practical Solutions that will help you to understand the logic behind PHP in a different way.

Some useful functions
PHP error types
Class concept
Access specifiers public, private and protected
Set variable with php.ini file
Operators introduced in PHP7
Logic and its output behind some code segment
Basic knowledge
PHP7, XAMPP Server, Notepad++
What will you learn
This course is build for the person who is facing interviews. Every question is well explained with the practical solution through videos. So that everybody can prepare themselves for the tricky questions asked during interviews
To continue:

#php-interview-questions-with-solutions #php-interview-questions #php #interview-questions

Martin  Dreech

Martin Dreech

1563433696

PHP Interview Questions - Top 100 Questions and Answers for PHP Developers

PHP is the most popular scripting language on the web. Without PHP Facebook, Yahoo, Google wouldn’t have exist. The course is geared to make you a PHP pro. Once you digest all basics, the course will help you create your very own Opinion Poll application.

1) What is PHP?

PHP is a web language based on scripts that allow developers to dynamically create generated web pages.

2) What do the initials of PHP stand for?

PHP means PHP: Hypertext Preprocessor.

3) Which programming language does PHP resemble?

PHP syntax resembles Perl and C

4) What does PEAR stand for?

PEAR means “PHP Extension and Application Repository”. It extends PHP and provides a higher level of programming for web developers.

5) What is the actually used PHP version?

Version 7.1 or 7.2 is the recommended version of PHP.

6) How do you execute a PHP script from the command line?

Just use the PHP command line interface (CLI) and specify the file name of the script to be executed as follows:

php script.php

7) How to run the interactive PHP shell from the command line interface?

Just use the PHP CLI program with the option -a as follows:

php -a

8) What is the correct and the most two common way to start and finish a PHP block of code?

The two most common ways to start and finish a PHP script are:

 <?php [   ---  PHP code---- ] ?> and <? [---  PHP code  ---] ?>

9) How can we display the output directly to the browser?

To be able to display the output directly to the browser, we have to use the special tags <?= and ?>.

10) What is the main difference between PHP 4 and PHP 5?

PHP 5 presents many additional OOP (Object Oriented Programming) features.

11) Is multiple inheritance supported in PHP?

PHP supports only single inheritance; it means that a class can be extended from only one single class using the keyword ‘extended’.

12) What is the meaning of a final class and a final method?

‘final’ is introduced in PHP5. Final class means that this class cannot be extended and a final method cannot be overridden.

13) How is the comparison of objects done in PHP?

We use the operator ‘==’ to test is two objects are instanced from the same class and have same attributes and equal values. We can test if two objects are referring to the same instance of the same class by the use of the identity operator ‘===’.

14) How can PHP and HTML interact?

It is possible to generate HTML through PHP scripts, and it is possible to pass pieces of information from HTML to PHP.

15) What type of operation is needed when passing values through a form or an URL?

If we would like to pass values through a form or an URL, then we need to encode and to decode them using htmlspecialchars() and urlencode().

16) How can PHP and Javascript interact?

PHP and Javascript cannot directly interact since PHP is a server side language and Javascript is a client-side language. However, we can exchange variables since PHP can generate Javascript code to be executed by the browser and it is possible to pass specific variables back to PHP via the URL.

17) What is needed to be able to use image function?

GD library is needed to execute image functions.

18) What is the use of the function ‘imagetypes()’?

imagetypes() gives the image format and types supported by the current version of GD-PHP.

19) What are the functions to be used to get the image’s properties (size, width, and height)?

The functions are getimagesize() for size, imagesx() for width and imagesy() for height.

20) How failures in execution are handled with include() and require() functions?

If the function require() cannot access the file then it ends with a fatal error. However, the include() function gives a warning, and the PHP script continues to execute.

21) What is the main difference between require() and require_once()?

require(), and require_once() perform the same task except that the second function checks if the PHP script is already included or not before executing it.

(same for include_once() and include())

22) How can I display text with a PHP script?

Two methods are possible:

<!--?php echo "Method 1"; print "Method 2"; ?-->

23) How can we display information of a variable and readable by a human with PHP?

To be able to display a human-readable result we use print_r().

24) How is it possible to set an infinite execution time for PHP script?

The set_time_limit(0) added at the beginning of a script sets to infinite the time of execution to not have the PHP error ‘maximum execution time exceeded.’ It is also possible to specify this in the php.ini file.

25) What does the PHP error ‘Parse error in PHP – unexpected T_variable at line x’ means?

This is a PHP syntax error expressing that a mistake at the line x stops parsing and executing the program.

26) What should we do to be able to export data into an Excel file?

The most common and used way is to get data into a format supported by Excel. For example, it is possible to write a .csv file, to choose for example comma as a separator between fields and then to open the file with Excel.

27) What is the function file_get_contents() useful for?

file_get_contents() lets reading a file and storing it in a string variable.

28) How can we connect to a MySQL database from a PHP script?

To be able to connect to a MySQL database, we must use mysqli_connect() function as follows:

<!--?php $database = mysqli_connect("HOST", "USER_NAME", "PASSWORD"); mysqli_select_db($database,"DATABASE_NAME"); ?-->

29) What is the function mysql_pconnect() useful for?

mysql_pconnect() ensure a persistent connection to the database, it means that the connection does not close when the PHP script ends.

This function is not supported in PHP 7.0 and above

30) How be the result set of Mysql handled in PHP?

The result set can be handled using mysqli_fetch_array, mysqli_fetch_assoc, mysqli_fetch_object or mysqli_fetch_row.

31) How is it possible to know the number of rows returned in the result set?

The function mysqli_num_rows() returns the number of rows in a result set.

32) Which function gives us the number of affected entries by a query?

mysqli_affected_rows() return the number of entries affected by an SQL query.

33) What is the difference between mysqli_fetch_object() and mysqli_fetch_array()?

The mysqli_fetch_object() function collects the first single matching record where mysqli_fetch_array() collects all matching records from the table in an array.

34) How can we access the data sent through the URL with the GET method?

To access the data sent via the GET method, we use $_GET array like this:

www.url.com?var=value
$variable = $_GET["var"]; this will now contain 'value'

35) How can we access the data sent through the URL with the POST method?

To access the data sent this way, you use the $_POST array.

Imagine you have a form field called ‘var’ on the form when the user clicks submit to the post form, you can then access the value like this:

$_POST["var"];

36) How can we check the value of a given variable is a number?

It is possible to use the dedicated function, is_numeric() to check whether it is a number or not.

37) How can we check the value of a given variable is alphanumeric?

It is possible to use the dedicated function, ctype_alnum to check whether it is an alphanumeric value or not.

38) How do I check if a given variable is empty?

If we want to check whether a variable has a value or not, it is possible to use the empty() function.

39) What does the unlink() function mean?

The unlink() function is dedicated for file system handling. It simply deletes the file given as entry.

40) What does the unset() function mean?

The unset() function is dedicated for variable management. It will make a variable undefined.

41) How do I escape data before storing it in the database?

The addslashes function enables us to escape data before storage into the database.

42) How is it possible to remove escape characters from a string?

The stripslashes function enables us to remove the escape characters before apostrophes in a string.

43) How can we automatically escape incoming data?

We have to enable the Magic quotes entry in the configuration file of PHP.

44) What does the function get_magic_quotes_gpc() means?

The function get_magic_quotes_gpc() tells us whether the magic quotes is switched on or no.

45) Is it possible to remove the HTML tags from data?

The strip_tags() function enables us to clean a string from the HTML tags.

46) what is the static variable in function useful for?

A static variable is defined within a function only the first time, and its value can be modified during function calls as follows:

<!--?php function testFunction() { static $testVariable = 1; echo $testVariable; $testVariable++; } testFunction();        //1 testFunction();        //2 testFunction();        //3 ?-->

47) How can we define a variable accessible in functions of a PHP script?

This feature is possible using the global keyword.

48) How is it possible to return a value from a function?

A function returns a value using the instruction ‘return $value;’.

49) What is the most convenient hashing method to be used to hash passwords?

It is preferable to use crypt() which natively supports several hashing algorithms or the function hash() which supports more variants than crypt() rather than using the common hashing algorithms such as md5, sha1 or sha256 because they are conceived to be fast. Hence, hashing passwords with these algorithms can create vulnerability.

50) Which cryptographic extension provide generation and verification of digital signatures?

The PHP-OpenSSL extension provides several cryptographic operations including generation and verification of digital signatures.

51) How is a constant defined in a PHP script?

The define() directive lets us defining a constant as follows:

define ("ACONSTANT", 123);

52) How can you pass a variable by reference?

To be able to pass a variable by reference, we use an ampersand in front of it, as follows $var1 = &$var2

53) Will a comparison of an integer 12 and a string “13” work in PHP?

“13” and 12 can be compared in PHP since it casts everything to the integer type.

54) How is it possible to cast types in PHP?

The name of the output type has to be specified in parentheses before the variable which is to be cast as follows:

* (int), (integer) – cast to integer

* (bool), (boolean) – cast to boolean

* (float), (double), (real) – cast to float

* (string) – cast to string

* (array) – cast to array

* (object) – cast to object

55) When is a conditional statement ended with endif?

When the original if was followed by: and then the code block without braces.

56) How is the ternary conditional operator used in PHP?

It is composed of three expressions: a condition, and two operands describing what instruction should be performed when the specified condition is true or false as follows:

Expression_1?Expression_2 : Expression_3;

57) What is the function func_num_args() used for?

The function func_num_args() is used to give the number of parameters passed into a function.

58) If the variable $var1 is set to 10 and the $var2 is set to the character var1, what’s the value of $$var2?

$$var2 contains the value 10.

59) What does accessing a class via :: means?

:: is used to access static methods that do not require object initialization.

60) In PHP, objects are they passed by value or by reference?

In PHP, objects passed by value.

61) Are Parent constructors called implicitly inside a class constructor?

No, a parent constructor have to be called explicitly as follows:

parent::constructor($value)

62) What’s the difference between __sleep and __wakeup?

__sleep returns the array of all the variables that need to be saved, while __wakeup retrieves them.

63) What is faster?

1- Combining two variables as follows:

$variable1 = 'Hello ';

$variable2 = ‘World’;

$variable3 = $variable1.$variable2;

Or

2- $variable3 = “$variable1$variable2”;

$variable3 will contain “Hello World”. The first code is faster than the second code especially for large large sets of data.

64) what is the definition of a session?

A session is a logical object enabling us to preserve temporary data across multiple PHP pages.

65) How to initiate a session in PHP?

The use of the function session_start() lets us activating a session.

66) How can you propagate a session id?

You can propagate a session id via cookies or URL parameters.

67) What is the meaning of a Persistent Cookie?

A persistent cookie is permanently stored in a cookie file on the browser’s computer. By default, cookies are temporary and are erased if we close the browser.

68) When do sessions end?

Sessions automatically end when the PHP script finishes executing but can be manually ended using the session_write_close().

69) What is the difference between session_unregister() and session_unset()?

The session_unregister() function unregister a global variable from the current session and the session_unset() function frees all session variables.

70) What does $GLOBALS mean?

$GLOBALS is associative array including references to all variables which are currently defined in the global scope of the script.

71) What does $_SERVER mean?

$_SERVER is an array including information created by the web server such as paths, headers, and script locations.

72) What does $_FILES means?

$_FILES is an associative array composed of items sent to the current script via the HTTP POST method.

73) What is the difference between $_FILES[‘userfile’][‘name’] and $_FILES[‘userfile’][‘tmp_name’]?

$_FILES[‘userfile’][‘name’] represents the original name of the file on the client machine,

$_FILES[‘userfile’][‘tmp_name’] represents the temporary filename of the file stored on the server.

74) How can we get the error when there is a problem to upload a file?

$_FILES[‘userfile’][‘error’] contains the error code associated with the uploaded file.

75) How can we change the maximum size of the files to be uploaded?

We can change the maximum size of files to be uploaded by changing upload_max_filesize in php.ini.

76) What does $_ENV mean?

$_ENV is an associative array of variables sent to the current PHP script via the environment method.

77) What does $_COOKIE mean?

$_COOKIE is an associative array of variables sent to the current PHP script using the HTTP Cookies.

78) What does the scope of variables mean?

The scope of a variable is the context within which it is defined. For the most part, all PHP variables only have a single scope. This single scope spans included and required files as well.

79) what the difference between the ‘BITWISE AND’ operator and the ‘LOGICAL AND’ operator?

$a and $b: TRUE if both $a and $b are TRUE.

$a & $b: Bits that are set in both $a and $b are set.

80) What are the two main string operators?

The first is the concatenation operator (‘.’), which returns the concatenation of its right and left arguments. The second is (‘.=’), which appends the argument on the right to the argument on the left.

81) What does the array operator ‘===’ means?

$a === $b TRUE if $a and $b have the same key/value pairs in the same order and of the same types.

82) What is the differences between $a != $b and $a !== $b?

!= means inequality (TRUE if $a is not equal to $b) and !== means non-identity (TRUE if $a is not identical to $b).

83) How can we determine whether a PHP variable is an instantiated object of a certain class?

To be able to verify whether a PHP variable is an instantiated object of a certain class we use instanceof.

84) What is the goto statement useful for?

The goto statement can be placed to enable jumping inside the PHP program. The target is pointed by a label followed by a colon, and the instruction is specified as a goto statement followed by the desired target label.

85) what is the difference between Exception::getMessage and Exception:: getLine?

Exception::getMessage lets us getting the Exception message and Exception::getLine lets us getting the line in which the exception occurred.

86) What does the expression Exception::__toString means?

Exception::__toString gives the String representation of the exception.

87) How is it possible to parse a configuration file?

The function parse_ini_file() enables us to load in the ini file specified in filename and returns the settings in it in an associative array.

88) How can we determine whether a variable is set?

The boolean function isset determines if a variable is set and is not NULL.

89) What is the difference between the functions strstr() and stristr()?

The string function strstr(string allString, string occ) returns part of allString from the first occurrence of occ to the end of allString. This function is case-sensitive. stristr() is identical to strstr() except that it is case insensitive.

90) what is the difference between for and foreach?

for is expressed as follows:

for (expr1; expr2; expr3)

statement

The first expression is executed once at the beginning. In each iteration, expr2 is evaluated. If it is TRUE, the loop continues, and the statements inside for are executed. If it evaluates to FALSE, the execution of the loop ends. expr3 is tested at the end of each iteration.

However, foreach provides an easy way to iterate over arrays, and it is only used with arrays and objects.

91) Is it possible to submit a form with a dedicated button?

It is possible to use the document.form.submit() function to submit the form. For example: <input type=button value=”SUBMIT” onClick=”document.form.submit()”>

92) What is the difference between ereg_replace() and eregi_replace()?

The function eregi_replace() is identical to the function ereg_replace() except that it ignores case distinction when matching alphabetic characters.

93) Is it possible to protect special characters in a query string?

Yes, we use the urlencode() function to be able to protect special characters.

94) What are the three classes of errors that can occur in PHP?

The three basic classes of errors are notices (non-critical), warnings (serious errors) and fatal errors (critical errors).

95) What is the difference between characters \034 and \x34?

\034 is octal 34 and \x34 is hex 34.

96) How can we pass the variable through the navigation between the pages?

It is possible to pass the variables between the PHP pages using sessions, cookies or hidden form fields.

97) Is it possible to extend the execution time of a PHP script?

The use of the set_time_limit(int seconds) enables us to extend the execution time of a PHP script. The default limit is 30 seconds.

98) Is it possible to destroy a cookie?

Yes, it is possible by setting the cookie with a past expiration time.

99) What is the default session time in PHP?

The default session time in php is until the closing of the browser

100) Is it possible to use COM component in PHP?

Yes, it’s possible to integrate (Distributed) Component Object Model components ((D)COM) in PHP scripts which is provided as a framework.

Thanks for reading. If you liked this post, share it with all of your programming buddies!

Further reading

PHP Interview Questions - Top 50 Questions for PHP Developers

☞ PHP for Beginners - Become a PHP Master - CMS Project

☞ Learn Object Oriented PHP By Building a Complete Website

☞ PHP OOP: Object Oriented Programming for beginners + Project

☞ Laravel PHP Framework Tutorial - Full Course for Beginners (2019)

☞ Laravel 5.8 Tutorial from Scratch for Beginners

☞ 50+ Java Interview Questions for Programmers

☞ Top 100 Python Interview Questions and Answers

☞ Top 100 Python Interview Questions and Answers

☞ Best 50 React Interview Questions and Answers in 2019

☞ Top 50+ SQL Interview Questions and Answers in 2019

☞ Best 50 Nodejs interview questions from Beginners to Advanced in 2019

☞ 100+ Java Interview Questions and Answers In 2019

☞ Best 50 React Interview Questions for Frontend Developers in 2019

☞ Best 50 Angular Interview Questions for Frontend Developers in 2019



This post was originally published here

#php #web-development #devops #interview-questions #interview #laravel

Toby Rogers

Toby Rogers

1563347654

PHP Interview Questions - Top 50 Questions for PHP Developers

PHP is a recursive acronym for PHP Hypertext Preprocessor. It is a widely used open-source programming language especially suited for creating dynamic websites and mobile API’s. So, if you are planning to start your career in PHP and you wish to know the skills related to it, now is the right time to dive in. These **PHP Interview Questions and Answers **are collected after consulting with **PHP Certification Training **experts.

The PHP Interview Questions are divided into 2 sections:
Basic Level PHP Interview QuestionsAdvanced Level PHP Interview Questions
Let’s begin with the first section of PHP interview questions.

Basic Level PHP Interview Questions

Q1. What are the common uses of PHP?

Q2. What is PEAR in PHP?

PEAR is a framework and repository for reusable PHP components. PEAR stands for PHP Extension and Application Repository. It contains all types of PHP code snippets and libraries. It also provides a command line interface to install “packages” automatically.

Q3. What is the difference between static and dynamic websites?

Q4. How to execute a PHP script from the command line?

To execute a PHP script, use the PHP Command Line Interface (CLI) and specify the file name of the script in the following way:

php script.php

Q5. Is PHP a case sensitive language?

PHP is partially case sensitive. The variable names are case-sensitive but function names are not. If you define the function name in lowercase and call them in uppercase, it will still work. User-defined functions are not case sensitive but the rest of the language is case-sensitive.

Q6. What is the meaning of ‘escaping to PHP’?

The PHP parsing engine needs a way to differentiate PHP code from other elements in the page. The mechanism for doing so is known as ‘escaping to PHP’. Escaping a string means to reduce ambiguity in quotes used in that string.

Q7. What are the characteristics of PHP variables?

Some of the important characteristics of PHP variables include:
All variables in PHP are denoted with a leading dollar sign ($).The value of a variable is the value of its most recent assignment.Variables are assigned with the = operator, with the variable on the left-hand side and the expression to be evaluated on the right.Variables can, but do not need, to be declared before assignment.Variables in PHP do not have intrinsic types – a variable does not know in advance whether it will be used to store a number or a string of characters.Variables used before they are assigned have default values.### Q8. What are the different types of PHP variables?

There are 8 data types in PHP which are used to construct the variables:
Integers − are whole numbers, without a decimal point, like 4195.Doubles − are floating-point numbers, like 3.14159 or 49.1.Booleans − have only two possible values either true or false.NULL − is a special type that only has one value: NULL.Strings − are sequences of characters, like ‘PHP supports string operations.’Arrays − are named and indexed collections of other values.Objects − are instances of programmer-defined classes, which can package up both other kinds of values and functions that are specific to the class.Resources − are special variables that hold references to resources external to PHP.### Q9. What are the rules for naming a PHP variable?

The following rules are needed to be followed while naming a PHP variable:
Variable names must begin with a letter or underscore character.A variable name can consist of numbers, letters, underscores but you cannot use characters like + , – , % , ( , ) . & , etc.### Q10. What are the rules to determine the “truth” of any value which is not already of the Boolean type?

The rules to determine the “truth” of any value which is not already of the Boolean type are:
If the value is a number, it is false if exactly equal to zero and true otherwise.If the value is a string, it is false if the string is empty (has zero characters) or is the string “0”, and is true otherwise.Values of type NULL are always false.If the value is an array, it is false if it contains no other values, and it is true otherwise. For an object, containing a value means having a member variable that has been assigned a value.Valid resources are true (although some functions that return resources when they are successful will return FALSE when unsuccessful).Don’t use double as Booleans.### Q11. What is NULL?

NULL is a special data type which can have only one value. A variable of data type NULL is a variable that has no value assigned to it. It can be assigned as follows:

$var = NULL;

The special constant NULL is capitalized by convention but actually it is case insensitive. So,you can also write it as :

$var = null;

A variable that has been assigned the NULL value, consists of the following properties:
It evaluates to FALSE in a Boolean context.It returns FALSE when tested with IsSet() function.### Q12. How do you define a constant in PHP?

To define a constant you have to use define() function and to retrieve the value of a constant, you have to simply specifying its name.If you have defined a constant, it can never be changed or undefined. There is no need to have a constant with a $. A valid constant name starts with a letter or underscore.

Q13. What is the purpose of constant() function?

The constant() function will return the value of the constant. This is useful when you want to retrieve value of a constant, but you do not know its name, i.e., it is stored in a variable or returned by a function. For example –

<?php
define("MINSIZE", 50);
echo MINSIZE;
echo constant("MINSIZE"); // same thing as the previous line
?>

Q14. What are the differences between PHP constants and variables?

Q15. Name some of the constants in PHP and their purpose.

  1. LINE – It represents the current line number of the file.
  2. ** FILE** – It represents the full path and filename of the file. If used inside an include,the name of the included file is returned.
  3. FUNCTION – It represents the function name.
  4. CLASS – It returns the class name as it was declared.
  5. METHOD – It represents the class method name.

Q16. What is the purpose of break and continue statement?

Break – It terminates the for loop or switch statement and transfers execution to the statement immediately following the for loop or switch.

Continue – It causes the loop to skip the remainder of its body and immediately retest its condition prior to reiterating.

Q17. What are the two most common ways to start and finish a PHP block of code?

The two most common ways to start and** finish** a PHP block of code are:

<?php [ --- PHP code---- ] ?>

<? [--- PHP code ---] ?>

Q18. What is the difference between PHP4 and PHP5?

Q19. What is the meaning of a final class and a final method?

The **final **keyword in a method declaration indicates that the method cannot be overridden by subclasses. A class that is declared final cannot be subclassed. This is particularly useful when we are creating an immutable class like the String class.Properties cannot be declared final, only classes and methods may be declared as final.

Q20. How can you compare objects in PHP?

We use the operator ‘==’ to test if two objects are** instanced** from the same class and have same attributes and equal values. We can also test if two objects are referring to the same instance of the same class by the use of the identity operator ‘===’.

Q21. How can PHP and Javascript interact?

PHP and Javascript cannot directly interact since PHP is a server side language and Javascript is a client-side language. However, we can exchange variables since PHP can generate Javascript code to be executed by the browser and it is possible to pass specific variables back to PHP via the URL.

Q22. How can PHP and HTML interact?

It is possible to generate HTML through PHP scripts, and it is possible to pass pieces of information from HTML to PHP. PHP is a server side language and HTML is a client side language so PHP executes on server side and gets its results as strings, arrays, objects and then we use them to display its values in HTML.

Q23. Name some of the popular frameworks in PHP.

Some of the popular frameworks in PHP are:

  • CakePHP
  • CodeIgniter
  • Yii 2
  • Symfony
  • Zend Framework

Q24. What are the data types in PHP?

PHP support 9 primitive data types:

Q25. What are constructor and destructor in PHP?

PHP constructor and destructor are special type functions which are automatically called when a PHP class object is created and destroyed. The constructor is the most useful of the two because it allows you to send parameters along when creating a new object, which can then be used to initialize variables on the object.

Here is an example of constructor and destructor in PHP:

<?php
class Foo {
 
private $name;
private $link;
 
public function __construct($name) {
$this->;name = $name;
}
 
public function setLink(Foo $link){
$this->;link = $link;
}
 
public function __destruct() {
echo 'Destroying: ', $this->name, PHP_EOL;
}
}
?>

Q26. What are include() and require() functions?

The Include() function is used to put data of one PHP file into another PHP file. If errors occur then the include() function produces a warning but does not stop the execution of the script and it will continue to execute.

The Require() function is also used to put data of one PHP file to another PHP file. If there are any errors then the require() function produces a warning and a fatal error and stops the execution of the script.

Q27. What is the main difference between require() and require_once()?

The require() includes and evaluates a specific file, while require_once() does that only if it has not been included before. The require_once() statement can be used to include a php file in another one, when you may need to include the called file more than once. So, require_once() is recommended to use when you want to include a file where you have a lot of functions.

Q28. What are different types of errors available in Php ?

The different types of error in PHP are:
E_ERROR– A fatal error that causes script termination.E_WARNING– Run-time warning that does not cause script termination.E_PARSE– Compile time parse error.E_NOTICE– Run time notice caused due to error in code.E_CORE_ERROR– Fatal errors that occur during PHP initial startup.E_CORE_WARNING– Warnings that occur during PHP initial startup.E_COMPILE_ERROR– Fatal compile-time errors indication problem with script.E_USER_ERROR– User-generated error message.E_USER_WARNING– User-generated warning message.E_USER_NOTICE- User-generated notice message.E_STRICT– Run-time notices.E_RECOVERABLE_ERROR– Catchable fatal error indicating a dangerous errorE_ALL– Catches all errors and warnings.### Q29. Explain the syntax for ‘foreach’ loop with example.

The foreach statement is used to loop through arrays. For each pass the value of the current array element is assigned to $value and the array pointer is moved by one and in the next pass next element will be processed.

Syntax-

foreach (array as value)
 {
 code to be executed;
 }

Example

<?php
$colors = array("blue", "white", "black");
 
foreach ($colors as $value) {
echo "$value <br>";
}
?>

Q30. What are the different types of Array in PHP?

There are 3 types of Arrays in PHP:
Indexed Array – An array with a numeric index is known as the indexed array. Values are stored and accessed in linear fashion.Associative Array – An array with strings as index is known as the associative array. This stores element values in association with key values rather than in a strict linear index order.Multidimensional Array – An array containing one or more arrays is known as multidimensional array. The values are accessed using multiple indices.### Q31. What is the difference between single quoted string and double quoted string?

Singly quoted strings are treated almost literally, whereas doubly quoted strings replace variables with their values as well as specially interpreting certain character sequences. For example

<?php
$variable = "name";
$statement = 'My $variable will not print!n';
print($statement);
print "<br/>;"
$statement = "My $variable will print!n"
print($statement);
?>

It will give the following output

My $variable will not print!

My name will print

Q32. How to concatenate two strings in PHP?

To concatenate two string variables together, we use the dot (.) operator.

<?php
$string1="Hello edureka";
$string2="123";
echo $string1 . " " . $string2;
?>

This will produce following result

Hello edureka 123

Q33. How is it possible to set an infinite execution time for PHP script?

The set_time_limit(0) added at the beginning of a script sets to infinite the time of execution to not have the PHP error ‘maximum execution time exceeded.’ It is also possible to specify this in the php.ini file.

Q34. What is the difference between “echo” and “print” in PHP?

PHP echo output one or more string. It is a language construct not a function. So use of parentheses is not required. But if you want to pass more than one parameter to echo, use of parentheses is required. Whereas, PHP print output a string. It is a language construct not a function. So use of parentheses is not required with the argument list. Unlike echo, it always returns 1.Echo can output one or more string but print can only output one string and always returns 1.Echo is faster than print because it does not return any value.### Q35. Name some of the functions in PHP.

Some of the functions in PHP include:
ereg() – The ereg() function searches a string specified by string for a string specified by pattern, returning true if the pattern is found, and false otherwise.ereg() – The ereg() function searches a string specified by string for a string specified by pattern, returning true if the pattern is found, and false otherwise.split() – The split() function will divide a string into various elements, the boundaries of each element based on the occurrence of pattern in string.preg_match() – The preg_match() function searches string for pattern, returning true if pattern exists, and false otherwise.preg_split() – The preg_split() function operates exactly like split(), except that regular expressions are accepted as input parameters for pattern.
These were some of the most commonly asked basic level PHP interview questions. Let’s move on to the next section of advanced level PHP interview questions.

Advanced level PHP Interview Questions

Q36. What is the main difference between asp net and PHP?

PHP is a programming language whereas ASP.NET is a programming** framework**. Websites developed by ASP.NET may use C#, but also other languages such as J#. ASP.NET is compiled whereas PHP is interpreted. ASP.NET is designed for windows machines, whereas PHP is platform free and typically runs on Linux servers.

Q37. What is the use of session and cookies in PHP?

A session is a global variable stored on the server. Each session is assigned a unique id which is used to retrieve stored values. Sessions have the capacity to store relatively large data compared to cookies. The session values are automatically deleted when the browser is closed.

Following example shows how to** create a cookie** in PHP

<?php
$cookie_value = "edureka";
setcookie("edureka", $cookie_value, time()+3600, "/your_usename/", "edureka.co", 1, 1);
if (isset($_COOKIE['cookie']))
echo $_COOKIE["edureka"];
?>

Following example shows how to start a session in PHP

<?php
session_start();
 
if( isset( $_SESSION['counter'] ) ) {
$_SESSION['counter'] += 1;
}else {
$_SESSION['counter'] = 1;
}
 
$msg = "You have visited this page". $_SESSION['counter'];
$msg .= "in this session.";
?>

Q38. What is overloading and overriding in PHP?

Overloading is defining functions that have similar signatures, yet have different parameters. Overriding is only pertinent to derived classes, where the parent class has defined a method and the derived class wishes to override that method. In PHP, you can only overload methods using the magic method __call.

Q40. What is the difference between $message and $$message in PHP?

They are both variables. But $message is a variable with a fixed name. $$message is a variable whose name is stored in $message. For example, if $message contains “var”, $$message is the same as $var.

Q41. How can we create a database using PHP and MySQL?

The basic steps to create MySQL database using PHP are:
Establish a connection to MySQL server from your PHP script.If the connection is successful, write a SQL query to create a database and store it in a string variable.Execute the query.### Q42. What is GET and POST method in PHP?

The GET method sends the encoded user information appended to the page request. The page and the encoded information are separated by the ? character. For example

http://www.test.com/index.htm?name1=value1&name2=value2

The POST method transfers information via HTTP headers. The information is encoded as described in case of GET method and put into a header called QUERY_STRING.

Q43. What is the difference between GET and POST method?

Q44. What is the use of callback in PHP?

PHP callback are functions that may be called dynamically by PHP. They are used by native functions such as array_map, usort, preg_replace_callback, etc. A callback function is a function that you create yourself, then pass to another function as an argument. Once it has access to your callback function, the receiving function can then call it whenever it needs to.

Here is a basic example of callback function

<?php
 
function thisFuncTakesACallback($callbackFunc)
{
echo "I'm going to call $callbackFunc!<br />";
$callbackFunc();
}
function thisFuncGetsCalled()
{
echo "I'm a callback function!<br />";
}
 
thisFuncTakesACallback( 'thisFuncGetsCalled' );
?>

Q45. What is a lambda function in PHP?

A lambda function is an anonymous PHP function that can be stored in a variable and passed as an argument to other functions or methods. A closure is a lambda function that is aware of its surrounding context. For example

$input = array(1, 2, 3, 4, 5);
$output = array_filter($input, function ($v) { return $v > 2; });

unction ($v) { return $v > 2; } is the lambda function definition. We can store it in a variable so that it can be reusable.

Q46. What are PHP Magic Methods/Functions?

In PHP all functions starting with __ names are magical functions/methods. These methods, identified by a two underscore prefix (__), function as interceptors that are automatically called when certain conditions are met. PHP provides a number of ‘magicmethods that allow you to do some pretty neat tricks in object oriented programming.

Here are list of** Magic Functions** available in PHP

Q47. How can you encrypt password using PHP?

The crypt () function is used to create one way encryption. It takes one input string and one optional parameter. The function is defined as: crypt (inputstring, salt), where inputstring consists of the string that has to be encrypted and salt is an optional parameter. PHP uses DES for encryption. The format is as follows:

<?php
$password = crypt('edureka');
print $password. "is the encrypted version of edureka";
?>

Q48. How to connect to a URL in PHP?

PHP provides a library called cURL that may already be included in the installation of PHP by default. cURL stands for client URL, and it allows you to connect to a URL and retrieve information from that page such as the HTML content of the page, the HTTP headers and their associated data.

Q49. What is Type hinting in PHP?

Type hinting is used to specify the expected data type of an argument in a function declaration. When you call the function, PHP will check whether or not the arguments are of the specified type. If not, the run-time will raise an error and execution will be halted.

Here is an example of type hinting

<?php
function sendEmail (Email $email)
{
$email->send();
}
?>

The example shows how to send Email function argument $email Type hinted of Email Class. It means to call this function you must have to pass an email object otherwise an error is generated.

Q50. What is the difference between runtime exception and compile time exception?

An exception that occurs at compile time is called a checked exception. This exception cannot be ignored and must be handled carefully. For example, if you use FileReader class to read data from the file and the file specified in class constructor does not exist, then a FileNotFoundException occurs and you will have to manage that exception. For the purpose, you will have to write the code in a try-catch block and handle the exception. On the other hand, an exception that occurs at runtime is called unchecked-exception.

With this, we have come to the end of PHP interview questions blog. I Hope these PHP Interview Questions will help you in your interviews. In case you have attended any PHP interview in the recent past, do paste those interview questions in the comments section and we’ll answer them. You can also comment below if you have any questions in your mind, which you might face in your PHP interview.

Thanks for reading

If you liked this post, share it with all of your programming buddies!

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#php #web-development #laravel #interview #interview-questions

Sigrid  Farrell

Sigrid Farrell

1623718560

Top 10 Critical Spring Boot Interview Questions and Answers [For Beginners & Experienced]

offers powerful features for the rapid development of deployment-ready applications. It is the most used and best java framework for the development of scalable microservices and web applications.

If you want to become a domain expert, you have come to the right place. We have curated some the most repeatedly asked spring boot interview questions and answers to help you ace the interview.

Basic Spring Boot Interview Questions And Answers

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#full stack development #interview question answer #spring boot interview questions answer #top spring boot interview questions #top 10 critical spring boot interview questions #answers