[G++]Call by Reference (ps: C無此功能)

#include "stdio.h"
#include "stdlib.h"

void swap(int &, int &);

void swap(int &a, int &b)
{
    int x;

    x = a;
    a = b;
    b = x;
}

int main()
{
    int m, n;
    m = 5;
    n = 7;
    printf("[Before] m = %d <-> n = %d \n", m, n);
    swap(m, n);
    printf("[After]  m = %d <-> n = %d \n", m, n);
    return 0;
}

=====Result=====
[Before] m =5 <-> n = 7 
[After]   m =7 <-> n = 5

(ps: C無call by reference 所以  **.c檔是無法編譯,需使用cpp檔)