#include <stdio.h>

void swap(int a,int b);
void _swap(int *a,int *b);
int main() {
    int x=3,y=5;
    printf("x = %d and y = %d\n",x,y);
    swap(x,y);
    printf("x = %d and y = %d\n",x,y);
    _swap(&x,&y);
    return 0;
}
//call by value
void swap(int a,int b){
    int t = a;
    a=b;
    b=t;
    printf("a = %d and b = %d\n",a,b);
}
//call by reference
void _swap(int *a, int *b){
    int t=*a;
    *a=*b;
    *b=t;
}