Swapping two numbers - call by refernce

swap.c

#include <stdio.h>

int swap(int* a, int* b){
    int temp;
    temp = *a;
    *a = *b;
    *b = temp;
    
}

void main(){
    int a=2,b=4;
    swap(&a,&b);
    printf("%d %d",a,b);
    
}