C++ Program .Write a program to call by value parameter are passed by using value.

#include<stdio.h>
#include<conio.h>
void swap(int a,int b);
void main()
{
int a,b;
clrscr();
printf("\n enter the value of a");
scanf("\n %d",&a);
printf("\n enter the value of b");
scanf("\n %d",&b);
swap(a,b);
getch();
}
void swap(int a1,int b1)
{
int temp;
temp=a1;
a1=b1;
b1=temp;
printf("\n swapped value is a1 %d",a1);
printf("\n swapped value is b1 %d",b1);
}