Call by Reference

//  this program illustrates how call by reference works. the value of
//  a formal parm is changed inside the function and the change is passed
//  back to the caller because the parameter is passed by reference. the
//  & in the type of the formal parm is what makes it a reference parm

#include <iostream.h>

void sample(int&);

int main()
{
   int num;

   num = 5;
   cout << "Before the call num = " << num << endl;
   sample(num);
   cout << "After the call num = " << num << endl;
   return 0;
}

//  sample changes the value of num and prints it
//  the change is returned to the caller since num is passed by reference
void sample(int& num)
{
   num = 10;
   cout << "Inside the function num is changed to " << num << endl;
}

Sample Execution:

Before the call num = 5
Inside the function num is changed to 10
After the call num = 10

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