Diving into NumPy - An Important Library Required for Data Science

NumPy, one of the most important and basic libraries used in data science and machine learning, It consists of functionalities for multidimensional arrays, high-level mathematical functions such as,

  • Linear algebra operations
  • Fourier transform
  • Random generators

and also NumPy array forms the fundamental data structure for scikit-learn. The core of NumPy is well optimized C-code, so the execution speed is increased in Python while using Numpy.

The fundamental package for scientific computing with Python — NumPy

This article consists of the basic operations and most commonly and frequently used operations in NumPy. The article would be beginner-friendly and also act as a refresher for intermediate and advanced.

Let’s start with NumPy by importing it,

import numpy as np

The as keyword makes np as the alias name of NumPy, so we could use np instead of NumPy. This is a common practice that saves time and makes it easier to work.

NumPy Arrays

For creating a NumPy array we could use thenp.array function to create it and dtype as an optional argument that changes the array to the required type. Here is a list of array data types. When the elements in the array are of different array data types, then the elements will be upcasted to the highest level type. This means that if an array input has mixed int and float elements, all the integers will be cast to their floating-point equivalents. If an array is mixed with int, float, and string elements, everything is cast to strings.

To cast an array to the required type we could use theastype function. The function’s required argument is the new type of array and to know the type of array we could use .dtype

#Using arange function
arr = np.arange(5)
print(arr)
#Output: [0 1 2 3 4]
arr = np.arange(2,8,2)
print(arr)
#Output: [2,4,6]

#Playing with shape and reshape
arr1 = np.arange(6)
print(arr1.shape)
#Output: (6,)
arr2 = np.reshape(arr1,(2,3))
print(arr2)
print("The shape of arr2 is',arr2.shape)
#Output: [[0 1 2]
##         [3 4 5]]
##         The shape of arr2 is (2, 3)
arr3 = np.reshape(arr2,(-1,3,2))
print(arr3)
print("The shape of arr3 is',arr3.shape)
#Output: [[[0 1]
##          [2 3]
##          [4 5]]]
##        The shape of arr3 is (1, 3, 2)

#Flattening an array
print(arr3.flatten())
#Output: [0 1 2 3 4 5]      

To copy an array we could use the inherent copy function and perform it. The NaN (Not a Number) value could also be used by using np.nan . The _nan _would act as a placeholder and will not take the _integer value. _If integer type is used while containing nan, it would result in an error.

NumPy Basics

NumPy provides an option to create ranged data arrays using np.arange. The function acts very similarly to the range function in Python and returns a 1D array. If a single number n is passed as an argument then it would return numbers ranging from 0 to n-1. If two numbers are passed as argument mand nit would return numbers ranging from mto n-1 . If three arguments are used m, n and s it will return numbers ranging from mto n-1 using step size s .

The shape function is used to know the shape of the array. While using reshape function it takes input array and new shape as the arguments. For example, if the number of elements in an array is 10 then the new shape should be (5,2) or (2,5) as they form the multiplicative result. We are allowed to use the special value of -1 in at most one dimension of the new shape. The dimension with -1 will take on the value necessary to allow the new shape to contain all the elements of the array.

The flatten function would reshape an array of any size into a 1D array.

#Using arange function
arr = np.arange(5)
print(arr)
#Output: [0 1 2 3 4]
arr = np.arange(2,8,2)
print(arr)
#Output: [2,4,6]

#Playing with shape and reshape
arr1 = np.arange(6)
print(arr1.shape)
#Output: (6,)
arr2 = np.reshape(arr1,(2,3))
print(arr2)
print("The shape of arr2 is',arr2.shape)
#Output: [[0 1 2]
##         [3 4 5]]
##         The shape of arr2 is (2, 3)
arr3 = np.reshape(arr2,(-1,3,2))
print(arr3)
print("The shape of arr3 is',arr3.shape)
#Output: [[[0 1]
##          [2 3]
##          [4 5]]]
##        The shape of arr3 is (1, 3, 2)

#Flattening an array
print(arr3.flatten())
#Output: [0 1 2 3 4 5]      

Math Operations

With the help of NumPy arrays, we can apply arithmetic, logical and other operations to each element in the array. This helps to modify a large amount of numeric data with only a few operations. NumPy arrays perform a basic arithmetic operation to every element in an array. Apart from the basic arithmetic function, NumPy can perform other trigonometric, hyperbolic, exponents, logarithms, and a lot more functions. These functions have been listed here.

arr1 = np.array([[3,4],[5,6]])
arr2 = np.array([[1,2],[3,4]])
#Performing addition operation
print(arr1+2)
#Output: [[5 6]
##         [7 8]]

#Performing power operation
print(arr1**2)
#Output: [[ 9 16]
##         [25 36]]

#Performing subtraction between two array
print(arr1-arr2)
#Output: [[2 2]
##         [2 2]]

#Performing basic multiplication
print(arr1*arr2)
#Output: [[ 3  8]
##         [15 24]]

#Performing exponential function
print(np.exp(arr1))
#Output: [[ 20.08553692  54.59815003]
##         [148.4131591  403.42879349]]

#Performing logarthimic function with base 10
arr3 = np.array([[10,100],[np.e,np.pi]])
print(np.log10(arr3))
#Output: [[1\.         2\.        ]
##         [0.43429448 0.49714987]]

#Raising 3 to power of each element in array
print(np.power(3,arr2))
#Output: [[ 3  9]
##         [27 81]]

#Performing matrix multiplication
print(np.matmul(arr1,arr2))
#Output:  [[15 22]
##          [23 34]]

The function np.exp performs a _base e exponential_ on an array and np.log10 performs logarithms on input array using _base 10_ . To do a regular power operation with any base, we use np.power . The first argument to the function is the base , while the second is the power . To perform matrix multiplication between two arrays we use np.matmul the function. The dimension of two input matrix in np.matmul must obey the principle of matrix multiplication . The second dimension of the first matrix must equal the first dimension of the second matrix, otherwise np.matmul will result in a ValueError .

#machine-learning #numpy #python #data-science #developer

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Diving into NumPy - An Important Library Required for Data Science
黎 飞

黎 飞

1656984600

如何将函数从 C++ 导出到 React Native

今天,我继续分享我在 Native Module 和 C++ 方面的经验。

由于我们将看到很多为移动平台编写的 C/C++ 库,因此我们需要将它们实现到我们的 iOS 或 React Native 应用程序中。这就是为什么我想写一篇关于如何将一个函数从 C++ 导出到 React Native 的文章,它易于理解并且为初学者节省了时间。我将从一个新的 react native 应用程序开始

1.新建一个react native app,打开你的终端运行

npx react-native init NativeModules

2. 打开 Xcode 并导航到 NativeModules/ios/NativeModule.xcworkspace

3. 在 C++ 端工作

创建一个新的 C++ 文件并命名Cpp_to_RN.cpp

当我们创建一个新的 C++ 文件时,Xcode 会Cpp_to_RN.hpp 为我们创建一个头文件

首先,打开“ Cpp_to_RN.hpp文件,并创建一个包含没有主体的函数的类。

#ifndef Cpp_to_RN_hpp
#define Cpp_to_RN_hpp#include <stdio.h>
#include <string>class Cpp_to_RN {
public:
    std::string sayHello();
};#endif /* Cpp_to_RN_hpp */

然后打开Cpp_to_RN.cpp文件,写一个简单的函数“ sayHello()

#include "Cpp_to_RN.hpp"
std::string Cpp_to_RN::sayHello(){
    return "Hello from CPP";
}

4. 处理包装 C++ 文件。

包装 C++ 文件并将它们导出到 IOS (swift) 端

一个。创建一个Objective C文件并命名Cpp_to_RN.m

重命名Cpp_to_RN.m Cpp_to_RN.mm

湾。打开WrapCpp_to_RN.mm 文件并编写将包装sayHelloC++ 文件中的函数的正文内容。

#import <Foundation/Foundation.h>
#import "WrapCpp_to_RN.h"
#import "Cpp_to_RN.hpp"@implementation WrapCpp_to_RN- (NSString *) sayHello {
  Cpp_to_RN fromCPP;
    std::string helloWorldMessage = fromCPP.sayHello();
    return [NSString
            stringWithCString:helloWorldMessage.c_str()
            encoding:NSUTF8StringEncoding];
}
@end

C。创建头文件并命名WrapCpp_to_RN.h

将函数导出wrapSayHello到 Swift 文件

#import <Foundation/Foundation.h>
@interface WrapCpp_to_RN : NSObject
- (NSString *) wrapSayHello;
@end

5. 在 iOS (Swift) 端工作

将 C++ 函数导出到 React Native

一个。创建一个 Swift 文件并命名SendCpp_to_RN.swift

注意:Xcode 会要求我们为我们创建一个NativeModules-Bridging-Header.h文件。

创建一个类SendCpp_to_RN并将其声明为NSObject

#import <Foundation/Foundation.h>
@interface WrapCpp_to_RN : NSObject
- (NSString *) wrapSayHello;
@end

编写一个函数requiresMainQueueSetup()来防止我们运行应用程序时出现警告

#import <Foundation/Foundation.h>
@interface WrapCpp_to_RN : NSObject
- (NSString *) wrapSayHello;
@end

编写一个函数来包装WrapCpp_to_RN()fromWrapCpp_to_RN.mm

import Foundation@objc(SendCpp_to_RN)
class SendCpp_to_RN : NSObject {
    
  @objc static func requiresMainQueueSetup() -> Bool {
        return false
    }
  
  @objc func fromCpp(_ successCallback: RCTResponseSenderBlock) -> Void {
    successCallback([NSNull(), WrapCpp_to_RN().wrapSayHello() as Any])
    }}

湾。将 Swift 文件中的包装函数导出到 React Native

创建一个 Objective C 文件以导出 Swift 类及其函数,使用Callback

#import <React/RCTBridgeModule.h>
#import <Foundation/Foundation.h>
#import "UIKit/UIKit.h"
@interface RCT_EXTERN_MODULE(SendCpp_to_RN, NSObject)RCT_EXTERN_METHOD(fromCpp:(RCTResponseSenderBlock)successCallback)@end

C。将 Swift 连接到 React Native,打开NativeModules-Bridging-Header.h 文件

#import <React/RCTBridgeModule.h>#import <React/RCTViewManager.h>#import "WrapCpp_to_RN.h"

6. 在 React Native 方面工作

调用 Swift 类及其函数

import React from 'react';
import {StyleSheet, Text, View, NativeModules, Button} from 'react-native';const App = () => {
  const onPress = () => {
    const {SendCpp_to_RN} = NativeModules;
    SendCpp_to_RN.fromCpp((_err, res) => console.log(res));
  };
  return (
    <View style={styles.container}>
      <Text> Practice !</Text>
      <Button title="C++ to React Native" color="#841584" onPress={onPress} />
    </View>
  );
};
const styles = StyleSheet.create({
  container: {
    flex: 1,
    justifyContent: 'center',
    alignItems: 'center',
  },
});
export default App;

我们完成了,只需运行应用程序

react-native run-ios

或者只需单击 Xcode 上的“运行”按钮,看看我们做了什么。

希望我的文章对您有所帮助,感谢您的阅读时间。

 来源:https ://betterprogramming.pub/native-modules-export-c-function-to-react-native-for-beginners-77e89934b210

#cpp #cplusplus #react 

坂本  篤司

坂本 篤司

1656981060

関数をC++からReactNativeにエクスポートする方法

今日も、ネイティブモジュールとC++での経験を共有し続けています。

多くのC/C ++ライブラリがモバイルプラットフォーム用に作成されているので、それらをiOSまたはReactNativeアプリケーションに実装する必要があります。そのため、関数をC++からReactNativeにエクスポートする方法についての記事を書きたいと思います。これは、理解しやすく、初心者の時間を節約できます。新しいreactネイティブアプリケーションから始めます

1.新しいreactネイティブアプリを作成し、ターミナルを開いて実行します

npx react-native init NativeModules

2. Xcodeを開き、NativeModules / ios/NativeModule.xcworkspaceに移動します

3.C++側での作業

新しいC++ファイルを作成し、名前を付けますCpp_to_RN.cpp

新しいC++ファイルを作成すると、XcodeはヘッダーファイルCpp_to_RN.hpp を作成します

まず、「Cpp_to_RN.hppファイルを開き、本体のない関数を含むクラスを作成します。

#ifndef Cpp_to_RN_hpp
#define Cpp_to_RN_hpp#include <stdio.h>
#include <string>class Cpp_to_RN {
public:
    std::string sayHello();
};#endif /* Cpp_to_RN_hpp */

次に、ファイルを開いてCpp_to_RN.cpp、単純な関数「sayHello()」を記述します。

#include "Cpp_to_RN.hpp"
std::string Cpp_to_RN::sayHello(){
    return "Hello from CPP";
}

4.C++ファイルのラッピングに取り組んでいます。

C ++ファイルをラップしてIOS(swift)側にエクスポートするには

a。ObjectiveCファイルを作成して名前を付けますCpp_to_RN.m

名前をに変更Cpp_to_RN.m します Cpp_to_RN.mm

b。ファイルを開き、C++ファイルからWrapCpp_to_RN.mm 関数をラップする本文のコンテンツを記述します。sayHello

#import <Foundation/Foundation.h>
#import "WrapCpp_to_RN.h"
#import "Cpp_to_RN.hpp"@implementation WrapCpp_to_RN- (NSString *) sayHello {
  Cpp_to_RN fromCPP;
    std::string helloWorldMessage = fromCPP.sayHello();
    return [NSString
            stringWithCString:helloWorldMessage.c_str()
            encoding:NSUTF8StringEncoding];
}
@end

c。ヘッダーファイルを作成し、名前を付けますWrapCpp_to_RN.h

wrapSayHello関数をSwiftファイルにエクスポートします

#import <Foundation/Foundation.h>
@interface WrapCpp_to_RN : NSObject
- (NSString *) wrapSayHello;
@end

5. iOS(Swift)側での作業

C++関数をReactNativeにエクスポートするには

a。Swiftファイルを作成し、名前を付けますSendCpp_to_RN.swift

注:Xcodeは、NativeModules-Bridging-Header.hファイルを作成するように要求します。

クラスSendCpp_to_RNを作成し、次のように宣言しますNSObject

#import <Foundation/Foundation.h>
@interface WrapCpp_to_RN : NSObject
- (NSString *) wrapSayHello;
@end

requiresMainQueueSetup()アプリケーション実行時の警告を防ぐ関数を作成する

#import <Foundation/Foundation.h>
@interface WrapCpp_to_RN : NSObject
- (NSString *) wrapSayHello;
@end

WrapCpp_to_RN()fromをラップする関数を記述しますWrapCpp_to_RN.mm

import Foundation@objc(SendCpp_to_RN)
class SendCpp_to_RN : NSObject {
    
  @objc static func requiresMainQueueSetup() -> Bool {
        return false
    }
  
  @objc func fromCpp(_ successCallback: RCTResponseSenderBlock) -> Void {
    successCallback([NSNull(), WrapCpp_to_RN().wrapSayHello() as Any])
    }}

b。Swiftファイルのラップ関数をReactNativeにエクスポートします

を使用してSwiftクラスとその関数をエクスポートするObjectiveCファイルを作成しますCallback

#import <React/RCTBridgeModule.h>
#import <Foundation/Foundation.h>
#import "UIKit/UIKit.h"
@interface RCT_EXTERN_MODULE(SendCpp_to_RN, NSObject)RCT_EXTERN_METHOD(fromCpp:(RCTResponseSenderBlock)successCallback)@end

c。SwiftをReactNativeに接続し、NativeModules-Bridging-Header.h ファイルを開きます

#import <React/RCTBridgeModule.h>#import <React/RCTViewManager.h>#import "WrapCpp_to_RN.h"

6.ReactNative側での作業

Swiftクラスとその関数を呼び出す

import React from 'react';
import {StyleSheet, Text, View, NativeModules, Button} from 'react-native';const App = () => {
  const onPress = () => {
    const {SendCpp_to_RN} = NativeModules;
    SendCpp_to_RN.fromCpp((_err, res) => console.log(res));
  };
  return (
    <View style={styles.container}>
      <Text> Practice !</Text>
      <Button title="C++ to React Native" color="#841584" onPress={onPress} />
    </View>
  );
};
const styles = StyleSheet.create({
  container: {
    flex: 1,
    justifyContent: 'center',
    alignItems: 'center',
  },
});
export default App;

これで完了です。アプリケーションを実行するだけです。

react-native run-ios

または、Xcodeの「実行」ボタンをクリックして、実行内容を確認してください。

私の記事がお役に立てば幸いです。お読みいただきありがとうございます。

 ソース:https ://betterprogramming.pub/native-modules-export-c-function-to-react-native-for-beginners-77e89934b210

#cpp #cplusplus #react 

Léon  Peltier

Léon Peltier

1656979200

Comment Exporter Une Fonction De C++ Vers React Native

Aujourd'hui, je continue à partager mon expérience avec le module natif et C++.

Comme nous verrons beaucoup de bibliothèques C/C++ écrire pour les plates-formes mobiles, nous devons les implémenter dans notre application iOS ou React Native. C'est pourquoi je souhaite écrire un article sur la façon d'exporter une fonction de C++ vers React Native, ce qui est facile à comprendre et fait gagner du temps aux débutants. Je vais commencer avec une nouvelle application native réactive

1. Créez une nouvelle application native React, ouvrez votre terminal et exécutez

npx react-native init NativeModules

2. Ouvrez Xcode et accédez à NativeModules/ios/NativeModule.xcworkspace

3. Travailler du côté C++

Créez un nouveau fichier C++ et nommez-leCpp_to_RN.cpp

Lorsque nous créons un nouveau fichier C++, Xcode créera un fichier d'en-tête Cpp_to_RN.hpp pour nous

Tout d'abord, ouvrez le fichier " Cpp_to_RN.hpp" et créez une classe qui inclut une fonction sans le corps.

#ifndef Cpp_to_RN_hpp
#define Cpp_to_RN_hpp#include <stdio.h>
#include <string>class Cpp_to_RN {
public:
    std::string sayHello();
};#endif /* Cpp_to_RN_hpp */

Ouvrez ensuite le Cpp_to_RN.cppfichier et écrivez une fonction simple " sayHello()"

#include "Cpp_to_RN.hpp"
std::string Cpp_to_RN::sayHello(){
    return "Hello from CPP";
}

4. Travail sur l'encapsulation du fichier C++.

Pour envelopper les fichiers C++ et les exporter vers le côté IOS (swift)

un. Créez un fichier Objective C et nommez-leCpp_to_RN.m

Renommez le Cpp_to_RN.m en Cpp_to_RN.mm

b. Ouvrez le WrapCpp_to_RN.mm fichier et écrivez le contenu du corps qui encapsulera la fonction sayHelloà partir du fichier C++.

#import <Foundation/Foundation.h>
#import "WrapCpp_to_RN.h"
#import "Cpp_to_RN.hpp"@implementation WrapCpp_to_RN- (NSString *) sayHello {
  Cpp_to_RN fromCPP;
    std::string helloWorldMessage = fromCPP.sayHello();
    return [NSString
            stringWithCString:helloWorldMessage.c_str()
            encoding:NSUTF8StringEncoding];
}
@end

c. Créez un fichier d'en-tête et nommez-leWrapCpp_to_RN.h

Exporter la wrapSayHellofonction vers le fichier Swift

#import <Foundation/Foundation.h>
@interface WrapCpp_to_RN : NSObject
- (NSString *) wrapSayHello;
@end

5. Travailler du côté iOS (Swift)

Pour exporter la fonction C++ vers React Native

un. Créez un fichier Swift et nommez-leSendCpp_to_RN.swift

Remarque : Xcode nous demandera de créer un NativeModules-Bridging-Header.hfichier pour nous.

Créez une classe SendCpp_to_RNet déclarez-la commeNSObject

#import <Foundation/Foundation.h>
@interface WrapCpp_to_RN : NSObject
- (NSString *) wrapSayHello;
@end

Écrire une fonction requiresMainQueueSetup()pour empêcher l'avertissement lorsque nous exécutons l'application

#import <Foundation/Foundation.h>
@interface WrapCpp_to_RN : NSObject
- (NSString *) wrapSayHello;
@end

Ecrire une fonction pour envelopper le WrapCpp_to_RN()fromWrapCpp_to_RN.mm

import Foundation@objc(SendCpp_to_RN)
class SendCpp_to_RN : NSObject {
    
  @objc static func requiresMainQueueSetup() -> Bool {
        return false
    }
  
  @objc func fromCpp(_ successCallback: RCTResponseSenderBlock) -> Void {
    successCallback([NSNull(), WrapCpp_to_RN().wrapSayHello() as Any])
    }}

b. Exporter une fonction wrap dans un fichier Swift vers React Native

Créez un fichier Objective C pour exporter la classe Swift et sa fonction à l'aide deCallback

#import <React/RCTBridgeModule.h>
#import <Foundation/Foundation.h>
#import "UIKit/UIKit.h"
@interface RCT_EXTERN_MODULE(SendCpp_to_RN, NSObject)RCT_EXTERN_METHOD(fromCpp:(RCTResponseSenderBlock)successCallback)@end

c. Connectez Swift à React Native, ouvrez le NativeModules-Bridging-Header.h fichier

#import <React/RCTBridgeModule.h>#import <React/RCTViewManager.h>#import "WrapCpp_to_RN.h"

6. Travailler du côté React Native

Appelez la classe Swift et ses fonctions

import React from 'react';
import {StyleSheet, Text, View, NativeModules, Button} from 'react-native';const App = () => {
  const onPress = () => {
    const {SendCpp_to_RN} = NativeModules;
    SendCpp_to_RN.fromCpp((_err, res) => console.log(res));
  };
  return (
    <View style={styles.container}>
      <Text> Practice !</Text>
      <Button title="C++ to React Native" color="#841584" onPress={onPress} />
    </View>
  );
};
const styles = StyleSheet.create({
  container: {
    flex: 1,
    justifyContent: 'center',
    alignItems: 'center',
  },
});
export default App;

Et nous avons terminé, il suffit de lancer l'application

react-native run-ios

Ou cliquez simplement sur le bouton "exécuter" sur Xcode et voyez ce que nous avons fait.

J'espère que mon article vous sera utile, merci pour le temps de lecture.

 Source : https://betterprogramming.pub/native-modules-export-c-function-to-react-native-for-beginners-77e89934b210

#cpp #cplusplus #react 

Cómo Exportar Una Función De C++ A React Native

Hoy sigo compartiendo mi experiencia con el Módulo Nativo y C++.

Dado que veremos muchas bibliotecas C/C++ escribiendo para las plataformas móviles, debemos implementarlas en nuestra aplicación iOS o React Native. Por eso quiero escribir un artículo sobre cómo exportar una función de C++ a React Native, que es fácil de entender y ahorra tiempo a los principiantes. Comenzaré con una nueva aplicación nativa de reacción.

1. Cree una nueva aplicación nativa de reacción, abra su terminal y ejecute

npx react-native init NativeModules

2. Abra Xcode y vaya a NativeModules/ios/NativeModule.xcworkspace

3. Trabajando en el lado de C++

Cree un nuevo archivo C++ y asígnele un nombreCpp_to_RN.cpp

Cuando creamos un nuevo archivo C++, Xcode creará un archivo de encabezado Cpp_to_RN.hpp para nosotros

Primero, abra el archivo " Cpp_to_RN.hpp" y cree una clase que incluya una función sin el cuerpo.

#ifndef Cpp_to_RN_hpp
#define Cpp_to_RN_hpp#include <stdio.h>
#include <string>class Cpp_to_RN {
public:
    std::string sayHello();
};#endif /* Cpp_to_RN_hpp */

Luego abre el Cpp_to_RN.cpparchivo y escribe una función simple “ sayHello()

#include "Cpp_to_RN.hpp"
std::string Cpp_to_RN::sayHello(){
    return "Hello from CPP";
}

4. Trabajando en el archivo Wrapping C++.

Para envolver los archivos C++ y exportarlos al lado IOS (swift)

una. Cree un archivo Objective C y asígnele un nombreCpp_to_RN.m

Renombrar el Cpp_to_RN.m a Cpp_to_RN.mm

b. Abra el WrapCpp_to_RN.mm archivo y escriba el contenido del cuerpo que envolverá la función sayHellodel archivo C++.

#import <Foundation/Foundation.h>
#import "WrapCpp_to_RN.h"
#import "Cpp_to_RN.hpp"@implementation WrapCpp_to_RN- (NSString *) sayHello {
  Cpp_to_RN fromCPP;
    std::string helloWorldMessage = fromCPP.sayHello();
    return [NSString
            stringWithCString:helloWorldMessage.c_str()
            encoding:NSUTF8StringEncoding];
}
@end

C. Cree un archivo de encabezado y asígnele un nombreWrapCpp_to_RN.h

Exportar la wrapSayHellofunción al archivo Swift

#import <Foundation/Foundation.h>
@interface WrapCpp_to_RN : NSObject
- (NSString *) wrapSayHello;
@end

5. Trabajando en el lado de iOS (Swift)

Para exportar la función C++ a React Native

una. Cree un archivo Swift y asígnele un nombreSendCpp_to_RN.swift

Nota: Xcode nos pedirá que creemos un NativeModules-Bridging-Header.harchivo para nosotros.

Crear una clase SendCpp_to_RNy declararla comoNSObject

#import <Foundation/Foundation.h>
@interface WrapCpp_to_RN : NSObject
- (NSString *) wrapSayHello;
@end

Escribir una función requiresMainQueueSetup()para evitar advertencias cuando ejecutamos la aplicación.

#import <Foundation/Foundation.h>
@interface WrapCpp_to_RN : NSObject
- (NSString *) wrapSayHello;
@end

Escriba una función para envolver el WrapCpp_to_RN()fromWrapCpp_to_RN.mm

import Foundation@objc(SendCpp_to_RN)
class SendCpp_to_RN : NSObject {
    
  @objc static func requiresMainQueueSetup() -> Bool {
        return false
    }
  
  @objc func fromCpp(_ successCallback: RCTResponseSenderBlock) -> Void {
    successCallback([NSNull(), WrapCpp_to_RN().wrapSayHello() as Any])
    }}

b. Exporte una función de ajuste en un archivo Swift a React Native

Cree un archivo Objective C para exportar la clase Swift y su función usandoCallback

#import <React/RCTBridgeModule.h>
#import <Foundation/Foundation.h>
#import "UIKit/UIKit.h"
@interface RCT_EXTERN_MODULE(SendCpp_to_RN, NSObject)RCT_EXTERN_METHOD(fromCpp:(RCTResponseSenderBlock)successCallback)@end

C. Conecte Swift a React Native, abra el NativeModules-Bridging-Header.h archivo

#import <React/RCTBridgeModule.h>#import <React/RCTViewManager.h>#import "WrapCpp_to_RN.h"

6. Trabajando en el lado de React Native

Llame a la clase Swift y sus funciones

import React from 'react';
import {StyleSheet, Text, View, NativeModules, Button} from 'react-native';const App = () => {
  const onPress = () => {
    const {SendCpp_to_RN} = NativeModules;
    SendCpp_to_RN.fromCpp((_err, res) => console.log(res));
  };
  return (
    <View style={styles.container}>
      <Text> Practice !</Text>
      <Button title="C++ to React Native" color="#841584" onPress={onPress} />
    </View>
  );
};
const styles = StyleSheet.create({
  container: {
    flex: 1,
    justifyContent: 'center',
    alignItems: 'center',
  },
});
export default App;

Y listo, solo ejecuta la aplicación

react-native run-ios

O simplemente haga clic en el botón "ejecutar" en Xcode y vea lo que hemos hecho.

Espero que mi artículo te sea útil, gracias por tu tiempo de lectura.

 Fuente: https://betterprogramming.pub/native-modules-export-c-function-to-react-native-for-beginners-77e89934b210

#cpp #cplusplus #react 

Hoang  Ha

Hoang Ha

1656981000

Cách Xuất Một Hàm Từ C ++ Sang React Native

Hôm nay, tôi tiếp tục chia sẻ kinh nghiệm của mình với Native Module và C ++.

Vì chúng ta sẽ thấy rất nhiều thư viện C / C ++ viết cho nền tảng di động, chúng ta cần triển khai chúng cho ứng dụng iOS hoặc React Native của mình. Đó là lý do mình muốn viết một bài hướng dẫn cách export một hàm từ C ++ sang React Native dễ hiểu và tiết kiệm thời gian cho người mới bắt đầu. Tôi sẽ bắt đầu với một ứng dụng gốc phản ứng mới

1. Tạo một ứng dụng gốc phản ứng mới, mở thiết bị đầu cuối của bạn và chạy

npx react-native init NativeModules

2. Mở Xcode và điều hướng đến NativeModules / ios / NativeModule.xcworkspace

3. Làm việc trên C ++

Tạo một tệp C ++ mới và đặt tên cho nóCpp_to_RN.cpp

Khi chúng tôi tạo tệp C ++ mới, Xcode sẽ tạo tệp tiêu đề Cpp_to_RN.hpp cho chúng tôi

Đầu tiên, mở tệp Cpp_to_RN.hpp“” và tạo một lớp bao gồm một hàm không có phần thân.

#ifndef Cpp_to_RN_hpp
#define Cpp_to_RN_hpp#include <stdio.h>
#include <string>class Cpp_to_RN {
public:
    std::string sayHello();
};#endif /* Cpp_to_RN_hpp */

Sau đó, mở Cpp_to_RN.cpptệp và viết một hàm đơn giản “ sayHello()

#include "Cpp_to_RN.hpp"
std::string Cpp_to_RN::sayHello(){
    return "Hello from CPP";
}

4. Thao tác trên Wrapping C ++ file.

Để bọc các tệp C ++ và xuất chúng sang phía IOS (nhanh chóng)

một. Tạo một tệp Objective C và đặt tên cho nóCpp_to_RN.m

Đổi tên Cpp_to_RN.m thành Cpp_to_RN.mm

b. Mở WrapCpp_to_RN.mm tệp và viết nội dung phần nội dung sẽ bọc hàm sayHellotừ tệp C ++.

#import <Foundation/Foundation.h>
#import "WrapCpp_to_RN.h"
#import "Cpp_to_RN.hpp"@implementation WrapCpp_to_RN- (NSString *) sayHello {
  Cpp_to_RN fromCPP;
    std::string helloWorldMessage = fromCPP.sayHello();
    return [NSString
            stringWithCString:helloWorldMessage.c_str()
            encoding:NSUTF8StringEncoding];
}
@end

c. Tạo một tệp tiêu đề và đặt tên cho nóWrapCpp_to_RN.h

Xuất wrapSayHellohàm sang tệp Swift

#import <Foundation/Foundation.h>
@interface WrapCpp_to_RN : NSObject
- (NSString *) wrapSayHello;
@end

5. Làm việc trên iOS (Swift)

Để xuất hàm C ++ sang React Native

một. Tạo một tệp Swift và đặt tên cho nóSendCpp_to_RN.swift

Lưu ý: Xcode sẽ yêu cầu chúng tôi tạo một NativeModules-Bridging-Header.htệp cho chúng tôi.

Tạo một lớp SendCpp_to_RNvà khai báo nó làNSObject

#import <Foundation/Foundation.h>
@interface WrapCpp_to_RN : NSObject
- (NSString *) wrapSayHello;
@end

Viết một hàm requiresMainQueueSetup()để ngăn cảnh báo khi chúng tôi chạy ứng dụng

#import <Foundation/Foundation.h>
@interface WrapCpp_to_RN : NSObject
- (NSString *) wrapSayHello;
@end

Viết một hàm để bọc WrapCpp_to_RN()từWrapCpp_to_RN.mm

import Foundation@objc(SendCpp_to_RN)
class SendCpp_to_RN : NSObject {
    
  @objc static func requiresMainQueueSetup() -> Bool {
        return false
    }
  
  @objc func fromCpp(_ successCallback: RCTResponseSenderBlock) -> Void {
    successCallback([NSNull(), WrapCpp_to_RN().wrapSayHello() as Any])
    }}

b. Xuất một hàm bọc trong tệp Swift sang React Native

Tạo một tệp Objective C để xuất lớp Swift và chức năng của nó bằng cách sử dụngCallback

#import <React/RCTBridgeModule.h>
#import <Foundation/Foundation.h>
#import "UIKit/UIKit.h"
@interface RCT_EXTERN_MODULE(SendCpp_to_RN, NSObject)RCT_EXTERN_METHOD(fromCpp:(RCTResponseSenderBlock)successCallback)@end

c. Kết nối Swift với React Native, mở NativeModules-Bridging-Header.h tệp

#import <React/RCTBridgeModule.h>#import <React/RCTViewManager.h>#import "WrapCpp_to_RN.h"

6. Làm việc ở phía React Native

Gọi lớp Swift và các chức năng của nó

import React from 'react';
import {StyleSheet, Text, View, NativeModules, Button} from 'react-native';const App = () => {
  const onPress = () => {
    const {SendCpp_to_RN} = NativeModules;
    SendCpp_to_RN.fromCpp((_err, res) => console.log(res));
  };
  return (
    <View style={styles.container}>
      <Text> Practice !</Text>
      <Button title="C++ to React Native" color="#841584" onPress={onPress} />
    </View>
  );
};
const styles = StyleSheet.create({
  container: {
    flex: 1,
    justifyContent: 'center',
    alignItems: 'center',
  },
});
export default App;

Và chúng tôi đã hoàn tất, chỉ cần chạy ứng dụng

react-native run-ios

Hoặc chỉ cần nhấp vào nút “chạy” trên Xcode và xem những gì chúng tôi đã làm.

Tôi hy vọng bài viết của tôi hữu ích cho bạn, cảm ơn bạn đã dành thời gian đọc.

 Nguồn: https://betterprogramming.pub/native-modules-export-c- Chức năng-to-react-native-for-beginners-77e89934b210

#cpp #cplusplus #react