C++获取系统时间

1. //由于使用了windows.h，所以这种方法只能在windows系统下使用，不能在Mac或linux下使用?
   

    #include "iostream"  
    #include "windows.h"  
    #include "string"  
    using namespace std;  
      
    int main(){  
        SYSTEMTIME ct;  
        GetLocalTime(&ct);;//如果用GetSystemTime(&ct),则获取的是格林尼治时间  
      
        int year = ct.wYear;   
        int month = ct.wMonth;  
        int day = ct.wDay;  
        int hour = ct.wHour;  
        int minute = ct.wMinute;  
        int second = ct.wSecond;  
          
        cout << year << "/" << month << "/" << day << " "  
            << hour << ":" << minute << ":" << second << endl;  
      
        //把时间转换成字符串  
        char tmp[100];  
        sprintf_s(tmp,"%d/%d/%d %d:%d:%d",year,month,day,hour,minute,second);  
      
        string s = tmp;  
        cout << s << endl;  
        cout << tmp << endl;  
      
        return 0;  
    }