static 关键字

#include "stdafx.h"
#include <iostream>
#include <string>
using namespace std;
string language = "us";
void display();
int main()
{
    cout << "language in main: " << language << endl;
    display();
    cin.get();
    return 0;
}

#include "stdafx.h"
#include <iostream>
#include <string>
using namespace std;
static string language = "cn";

void display()
{
    cout << "language in support: " << language << endl;
}