C语言实现两个变量交换值

#include <stdio.h>
#include <string.h>

void swap(void *,void *,int);
int main()
{
    int a = 10; 
    int b = 20; 
    printf("交换前:a[%d],b[%d]\n", a, b); 
    swap(&a, &b ,sizeof(int));
    printf("交换后:a[%d],b[%d]\n", a, b); 
    return 0;
}

void swap(void *ap, void *bp, int size)
{
    char buff[size];
    memset(buff, 0, sizeof(buff));
    memcpy(buff, ap, size);
    memcpy(ap, bp, size);
    memcpy(bp, buff, size);
}