What are Call by Value and Call by reference in C++ with Examples.

Call by Value and Call by reference in C++



Call by Value

In C++ the Call by Value method takes place , the called function creates its own copies of the original values that have been entered . 
Example of Call by value

int main()
{
int x =1;
cout<< "x="<<x;
ch(x);
cout<<"\n x="<<x;
return 0;
}
void ch(int b)
{
b=10;
}


Output

x=1;
x=1;

Any changes , that are made, occur on the called  function's copy of values  and are not reflected back to the calling function .

Call by Reference

In case of the Call by reference , the method accesses and works with the original values using their references. 

Any changes , that occur , take place on the original values and are reflected back to the calling code.




Example of Call by Reference 

int main()
{
int a = 1;
cout<< "x="<<x;
ch(a);
cout<<"\n x ="<<x;
return 0;
}
void ch(int &b)
{
b=10;
}

Output

x=1
x=10