formal argument is changed in the calling funtion but currosponding chnge does not takeplace in the calling function.

Formal argument is changed in the calling funtion but currosponding chnge does not takeplace in the calling function:

#include<stdio.h>
#include<conio.h>
void fun(int);
void main()
{
int a=30;
clrscr();
printf("\nThe Output is:");
fun(a);
printf("\n%d",a);
getch();
}
void fun(int b)
{
b=60;
printf("\n%d",b);

}

Output: