examples in c++

C++ Programs:
Pass-By-Value:

# include <iostream.h>
int sub(int);       //Function prototype
main()
{
int function_value;
int x = 99;
cout << "x before call: "<< x << endl;
function_value = sub(x);     //Call function
cout << "x after call: "<< x << endl;
cout << "The value returned from function is "
       << function_value <<endl;
}
// Definition of Function
int sub(int a)
{
   a = a * 10;
   return a;
}

The output will be

x before call: 99
x after call: 99
The value returned from function is 990

Pass-By-Reference:

# include <iostream.h>
int sub(int &);       //Function prototype
main()
{
int function_value;
int x = 99;
cout << "x before call: "<< x << endl;
function_value = sub(x);     //Call function
cout << "x after call: "<< x << endl;
cout << "The value returned from function is "
       << function_value <<endl;
}
// Definition of Function
int sub(int &a)
{
   a = a * 10;
   return a;
}

The output will be

x before call: 99
x after call: 990
The value returned from function is 990

Pass-By-Pointers:

# include <iostream.h>
int sub(int *);       //Function prototype
main()
{
int function_value;
int x = 99;
cout << "x before call: "<< x << endl;
function_value = sub(&x);     //Call function
cout << "x after call: "<< x << endl;
cout << "The value returned from function is "
       << function_value <<endl;
}
// Definition of Function
int sub(int * a)
{
   *a = *a * 10;
   return *a;
}

The output will be

x before call: 99
x after call: 990
The value returned from function is 990

Note: Pass-By-Reference and Pass-By-Pointer get the same output.