C++ friend keyword

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VARAK-VURAK answered on April 3, 2022 Popularity 9/10 Helpfulness 1/10

answer C++ friend keyword

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C++ friend keyword

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// Add members of two different classes using friend functions

#include <iostream>
using namespace std;

// forward declaration
class ClassB;

class ClassA {
    
    public:
        // constructor to initialize numA to 12
        ClassA() : numA(12) {}
        
    private:
        int numA;
        
         // friend function declaration
         friend int add(ClassA, ClassB);
};

class ClassB {

    public:
        // constructor to initialize numB to 1
        ClassB() : numB(1) {}
    
    private:
        int numB;
 
        // friend function declaration
        friend int add(ClassA, ClassB);
};

// access members of both classes
int add(ClassA objectA, ClassB objectB) {
    return (objectA.numA + objectB.numB);
}

int main() {
    ClassA objectA;
    ClassB objectB;
    cout << "Sum: " << add(objectA, objectB);
    return 0;
}

Popularity 9/10 Helpfulness 1/10 Language cpp

Source: www.programiz.com

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Contributed on Sep 19 2022

VARAK-VURAK

0 Answers Avg Quality 2/10

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c++ friend class

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class A {
  	private:
      	int key;

 	// give class B access to class A
    friend class B;
};

class B {
	// new object from class A
  	A new_a;
  
  	void fn(){
		// access private value from class B
		new_a.key;
    }
}

Popularity 10/10 Helpfulness 4/10 Language cpp

Source: www.geeksforgeeks.org

Tags: c++

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Contributed on Apr 03 2022

ocean

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c++ friend function

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class Rectangle {
public:
  Rectangle(int width, int height) : width_(width), height_(height) {}

  friend int area(const Rectangle& rect);

private:
  int width_, height_;
};

int area(const Rectangle& rect) {
  return rect.width_ * rect.height_;
}

int main() {
  Rectangle rect(3, 4);
  int a = area(rect);
  return 0;
}

The main function creates a Rectangle object and then calls the area function with the object as its argument. Because the area function is a friend function of the Rectangle class, it has access to the private members of the object and can calculate the area of the rectangle.

By using friend functions in C++, you can provide access to the private and protected members of a class to functions that are not members of the class, while still maintaining the encapsulation of the class's data.

Popularity 10/10 Helpfulness 3/10 Language cpp

Source: Grepper

Tags: c++

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Contributed on Mar 07 2023

SubZero

0 Answers Avg Quality 2/10

Syntax of friend function in c++

Comment

class className {
    ... .. ...
    friend returnType functionName(arguments);
    ... .. ...
}

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Source: www.mygreatlearning.com

Tags: c++

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Contributed on Feb 24 2023

Sehrish Zarin

0 Answers Avg Quality 2/10

C++ friend keyword -3 (friend class)

Comment

// C++ program to demonstrate the working of friend class

#include <iostream>
using namespace std;

// forward declaration
class ClassB;

class ClassA {
    private:
        int numA;

        // friend class declaration
        friend class ClassB;

    public:
        // constructor to initialize numA to 12
        ClassA() : numA(12) {}
};

class ClassB {
    private:
        int numB;

    public:
        // constructor to initialize numB to 1
        ClassB() : numB(1) {}
    
    // member function to add numA
    // from ClassA and numB from ClassB
    int add() {
        ClassA objectA;
        return objectA.numA + numB;
    }
};

int main() {
    ClassB objectB;
    cout << "Sum: " << objectB.add();
    return 0;
}
//Sum: 13

Popularity 8/10 Helpfulness 2/10 Language cpp

Source: www.programiz.com

Tags: c++ friend fr

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Contributed on Sep 19 2022

VARAK-VURAK

0 Answers Avg Quality 2/10

C++ friend keyword

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C++ friend keyword -3 (friend class)

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