C++ Tutorial Index

C++ Tutorial C++ History C++ Installation C++ First Program C++ cin and cout C++ Data type C++ Variable C++ operator C++ Keywords

C++ Control Statements

C++ If C++ Nested if C++ If-else C++ If-else-if C++ Switch C++ Break C++ Continue C++ Goto C++ For loop C++ While loop C++ Do while loop

C++ Functions

C++ Call by Value C++ Call by Reference C++ Recursion Function C++ Inline function C++ Friend function

C++ Arrays

Single dimension array Two dimension array

C++ Strings

C++ Strings

C++ Inheritance

C++ Inheritance Single level Inheritance Multilevel Inheritance Multiple Inheritance Hierarchical Inheritance Hybrid Inheritance

C++ Polymorphism

C++ Polymorphism C++ Overloading C++ Overriding C++ Virtual Function

C++ Pointers

C++ Pointers C++ this pointer

C++ Exception Handling

C++ Exception Handling

C++ Constructors

C++ Constructors Default Constructor Parameterize Constructor Copy constructor Constructor Overloading Destructor

C++ File Handling

C++ File Handling C++ Writing to file C++ Reading file C++ Close file

Miscellaneous

C Vs C++ C++ Comments C++ Data Abstraction C++ Identifier C++ Memory Management C++ Storage Classes C++ Void Pointer C++ Array To Function C++ Expressions C++ Features C++ Interfaces C++ Encapsulation std::min in C++ External merge sort in C++ Remove duplicates from sorted array in C++ Precision of floating point numbers Using these functions floor(), ceil(), trunc(), round() and setprecision() in C++ C++ References C++ Friend Functions C++ Mutable keyword Unary Operators in C++ Initialize Array of objects with parameterized constructors in C++ Differences between #define & const in C/C++ C++ Program to Implement Shell Sort C++ Program to Implement Merge Sort Storage Classes in C Vector resize() in C++ Passing by Reference Vs. Passing by the pointer in C++ Free vs delete() in C++ goto statement in C and C++ C++ program to read string using cin.getline() C++ String Concatenation Heap Sort in C++ Swap numbers in C++ Input Iterators in C++ Fibonacci Series in C++ C ++ Program: Alphabet Triangle and Number Triangle C++ Program: Matrix Multiplication C++ Program to Print Fibonacci Triangle Stack in C++ Maps in C++ Queue in C++ C++ Bitset C++ Algorithms Priority Queue in C++ C++ Multimap C++ Deque Function Pointer in C++ Sizeof() Operators in C++ C++ array of Pointers free() Vs delete in C Timsort Implementation Using C++ CPP Templates C++ Aggregation C++ Enumeration C++ Math Functions C++ Object Class C++ Queue Initialize Vector in C++ Vector in C++ C++ STL Components Function overloading in C++ C++ Maximum Index Problem C++ find missing in the second array C++ Program to find the product array puzzle C++ Program To Find Largest Subarray With 0 Sum C++ Program To Move All Zeros To The End Of The Array C++ Program to find the element that occurs once C++ Program to find the largest number formed from an array Constructor Vs Destructor C++ Namespaces C++ OOPs Concept C++ Static C++ Structs C++ Try-Catch C++ User Defined Exceptions C++ Virtual Destructor C++ vs C# Malloc() and new in C++ Palindrome Number Program in C++ Snake Code in C++ Splitting a string in C++ Structure Vs Class in C++ Virtual Function Vs Pure Virtual Function C++ Bidirectional Iterators C++ Forward Iterators C++ Iterators C++ Output Iterators C++ Range-based For Loop Converting string into integer in C++ LCM Program in C++ Type conversion in C++ Add two numbers using the function in C++ Advantage and disadvantage friend function C++ Armstrong Number Program in C++ ATM machine program in C++ using functions Binary to Decimal in C++ Bit Manipulation in C++ C++ Constructor C++ Dijkstra Algorithm Using the Priority Queue C++ int into String C++ Signal Handling Decimal to Binary in C++ Decimal to Hexadecimal in C++ Decimal to Octal in C++ Factorial Program in C++ Function in C++ Hexadecimal to Decimal in C++ Octal to Decimal in C++ Reverse a Number in C++ Structure Vs Class in C++ C++ Forward Iterators C++ Output Iterators C++ Prime number program Constructor Overloading in C++ Different Ways to Compare Strings in C++ Program to convert infix to postfix expression in C++ SET Data Structure in C++ Upcasting and Downcasting in C++ Reverse an Array in C++ Fast Input and Output in C++ Delete Operator in C++ Copy elision in C++ C++ Date and Time C++ Bitwise XOR Operator Array of sets in C++ Binary Operator Overloading in C++ Binary Search in C++ Implementing the sets without C++ STL containers Scope Resolution Operator in C++ Smart pointers in C++ Types of polymorphism in C++

C++ Friend function

A friend function has the right to access all private and protected members of a class although it is defined outside that class' scope. Syntax

class className{  
  ......  
  friend retyrn_type function_Name(argument);  
  .......  
}  
return_type function_Name(argument){  
  ......  
}

C++ friend function Example

#include <iostream>  
using namespace std;  
class Length  
{  
    private:  
        int meter;  
    public:  
        Length(): meter(5) { }  
        friend int addMethod(Length); //friend function declaration  
};  
int addMethod(Length l) // friend function definition  
{  
    l.meter += 10; //accessing private data from non-member function  
    return l.meter;  
}  
int main()  
{  
    Length L;  
    int totallength;  
    totallength=addMethod(L);  
    cout<<"Length: "<< totallength;  
    return 0;  
}
Output:
Length: 15
 

C++ friend function in two different class

#include <iostream>  
using namespace std;  
class B;// forward declaration  
class A {  
    private:  
      int numA;  
    public:  
      A(): numA(5) { }  
      friend int add(A, B); // friend function declaration  
};  
class B {  
    private:  
       int numB;  
    public:  
       B(): numB(10) { }  
       friend int add(A , B); // friend function declaration  
};  
// Function add() is the friend function of classes A and B  
// that accesses the member variables numA and numB  
int add(A objectA, B objectB)  
{  
   return (objectA.numA + objectB.numB);  
}  
int main()  
{  
    A objectA;  
    B objectB;  
    cout<<"Sum: "<< add(objectA, objectB);  
    return 0;  
}
Output:
Sum: 15



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