C++,拆分.c.h文件

#include "a.h"

int fun(int x){
    return x;
}

#include <iostream>

using namespace std;
#define row 11
int fun(int x);

#include "a.h"

int main()
{
    cout << fun(2) << endl;
    cout << row << endl;
    return 0;
}