Call by Value in C

#include<stdio.h>
#include<conio.h>

main()
{
int a=10,b=20;
clrscr();
swap(a,b);
}
swap(int a,int b)
{
int t;
t=a;
a=b;
b=t;
printf("\n A Value is :%d",a);
printf("\n B Value is :%d",b);
}