In this python post, you will learn the following,What is a Linear Search? Linear Search Algorithm . Write a Python Program For Linear Search Using While Loop

- What is a Linear Search?
- Linear Search Algorithm
- Write a Python Program For Linear Search Using While Loop
- Write a Python Program For Linear Search Using For Loop
- Linear Search in Python Program using Recursion

First of all, A linear search, also known as a sequential search, this method is used to find an element within a list or array. It checks each element of the list one by one / sequentially until a match is found or the whole list has been searched.

Implement linear search following the below steps:

- Traverse the list/array using a loop.
- In every iteration, associate the
`target`

value with the given value of the list/array.- If the values match, return the current index of the list/array.
- Otherwise, move on to the next array/list element.

- If no match is found, return
`-1`

.

```
# python program for linear search using while loop
#define list
lst = []
#take input list size
num = int(input("Enter size of list :- "))
for n in range(num):
#append element in list/array
numbers = int(input("Enter the array of %d element :- " %n))
lst.append(numbers)
#take input number to be find in list
x = int(input("Enter number to search in list :- "))
i = 0
flag = False
while i < len(lst):
if lst[i] == x:
flag = True
break
i = i + 1
if flag == 1:
print('{} was found at index {}.'.format(x, i))
else:
print('{} was not found.'.format(x))
```

**After executing the program, the output will be:**

```
Enter size of list :- 5
Enter the array of 0 element :- 10
Enter the array of 1 element :- 23
Enter the array of 2 element :- 56
Enter the array of 3 element :- 89
Enter the array of 4 element :- 200
Enter number to search in list :- 89
89 was found at index 3.
```

```
# python program for linear search using for loop
#define list
lst = []
#take input list size
num = int(input("Enter size of list :- "))
for n in range(num):
#append element in list/array
numbers = int(input("Enter the array of %d element :- " %n))
lst.append(numbers)
#take input number to be find in list
x = int(input("Enter number to search in list :- "))
i = 0
flag = False
for i in range(len(lst)):
if lst[i] == x:
flag = True
break
if flag == 1:
print('{} was found at index {}.'.format(x, i))
else:
print('{} was not found.'.format(x))
```

**After executing the program, the output will be:**

```
Enter size of list :- 6
Enter the array of 0 element :- 25
Enter the array of 1 element :- 50
Enter the array of 2 element :- 100
Enter the array of 3 element :- 200
Enter the array of 4 element :- 250
Enter the array of 5 element :- 650
Enter number to search in list :- 200
200 was found at index 3.
```

```
# python program for linear search using for loop
#define list
lst = []
#take input list size
num = int(input("Enter size of list :- "))
for n in range(num):
#append element in list/array
numbers = int(input("Enter the array of %d element :- " %n))
lst.append(numbers)
#take input number to be find in list
x = int(input("Enter number to search in list :- "))
# Recursive function to linear search x in arr[l..r]
def recLinearSearch( arr, l, r, x):
if r < l:
return -1
if arr[l] == x:
return l
if arr[r] == x:
return r
return recLinearSearch(arr, l+1, r-1, x)
res = recLinearSearch(lst, 0, len(lst)-1, x)
if res != -1:
print('{} was found at index {}.'.format(x, res))
else:
print('{} was not found.'.format(x))
```

**After executing the program, the output will be:**

```
Enter size of list :- 5
Enter the array of 0 element :- 14
Enter the array of 1 element :- 25
Enter the array of 2 element :- 63
Enter the array of 3 element :- 42
Enter the array of 4 element :- 78
Enter number to search in list :- 78
78 was found at index 4.
```

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