header.h

#ifndef HEADER_H

#define HEADER_H

unsigned long getFac(unsigned short num);

static const unsigned short headerNum = ;

#endif // HEADER_H_INCLUDED

this.cpp

#include "header.h"

#include <iostream>

using namespace std;

extern unsigned short thatNum; //声明thatNum是来自外部的

static bool printMe = false;

int main()

{

    unsigned short thisNum = ;

    cout <<  thisNum << "i = " << getFac(thisNum) << endl;

    cout <<  thatNum << "i = " << getFac(thatNum) << endl;

    cout <<  headerNum << "i = " << getFac(headerNum) << endl;

    if(printMe)

    {

        cout << "that.cpp -> printMe = true 发挥作用" << endl;

    }

    else

    {

        cout << "this.cpp -> static boolean printMe 发挥作用" << endl;

    }

    return ;

}

that.cpp

#include "header.h"

unsigned short thatNum = ;

bool printMe = true;

unsigned long getFac(unsigned short num)

{

    unsigned long sum = ;

    for (int i=; i<=num; i++)

    {

        sum *= i;

    }

    if(printMe)

    {

        return sum;

    }

    else

    {

        return ;

    }

}