Program Of Call By Value In C++

#include<iostream.h>

#include<conio.h>

int sum(int x,int y);  // Function Delaration

main()

{

clrscr();

int a,b,c;

cout<<"Enter First NUmber=";

cin>>a;

cout<<"Enter Second NUmber=";

cin>>b;

           c=sum(a,b);                 // Function CAlling

cout<<"\n NAswer="<<c;

getch();

}

        int sum(int x,int y)           // Function Define

{

int  z;

z=x+y;

return z;

}

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Passing a variable by value makes a copy of the 

variable before passing it onto a function. This means

that if you try to modify the value inside a function, it

 will only have the modified value inside that 

function. One the function returns, the variable you 

passed it will have the same value it had before you 

passed it into the function.