c++ 判断操作系统

#include <stdio.h>

#include <iostream>



using namespace std;



int main(int argc,char **argv){

    int no_os_flag=1;

    #ifdef linux

       no_os_flag=0;

       cout<<"It is in Linux OS!"<<endl;

    #endif

    #ifdef _UNIX

       no_os_flag=0;

       cout<<"It is in UNIX OS!"<<endl;

    #endif

    #ifdef __WINDOWS_

       no_os_flag=0;

       cout<<"It is in Windows OS!"<<endl;

    #endif

    #ifdef _WIN32

       no_os_flag=0;

       cout<<"It is in WIN32 OS!"<<endl;

    #endif

    if(1==no_os_flag){

        cout<<"No OS Defined ,I do not know what the os is!"<<endl;

    }
    system("systeminfo");
    return 0;

}