用C,C检测Windows或Linux

参见英文答案 > How do I check OS with a preprocessor directive?????????????????????????????????????16个
我正在编写一个跨平台程序.我希望这个程序在Windows和Linux下运行,所以我有两个不同的代码段用于这两个平台.如果操作系统是Windows,我想要运行第一个代码段;如果它是Linux,那么我希望第二个代码段运行.

所以我编写了以下代码,但在Windows和Linux上构建时都会出错.我该怎么做才能解决它？

#ifdef __unix__                    /* __unix__ is usually defined by compilers targeting Unix systems */

    #define OS_Windows 0
    #include <unistd.h>
    #include <stdlib.h>
    #include <stdio.h>
    #include <string.h>

#elif defined(_WIN32) || defined(WIN32)     /* _Win32 is usually defined by compilers targeting 32 or   64 bit Windows systems */

    #define OS_Windows 1
    #include <windows.h>
    #include <stdio.h>
    #include <tchar.h>
    #define DIV 1048576
    #define WIDTH 7

#endif

int main(int argc,char *argv[])
{
    if(OS_Windows)
    {
        MEMORYSTATUSEX statex;
        statex.dwLength = sizeof (statex);
        GlobalMemoryStatusEx (&statex);

        _tprintf (TEXT("There is  %*ld %% of memory in use.n"),WIDTH,statex.dwMemoryLoad);

    }

    else if(!OS_Windows) // if OS is unix

    {
        char cmd[30];
        int flag = 0;
        FILE *fp;
        char line[130];
        int memTotal,memFree,memUsed;

        flag=0;
        memcpy (cmd,"",30);
        sprintf(cmd,"free -t -m|grep Total");
        fp = popen(cmd,"r");
        while ( fgets( line,sizeof line,fp))
        {
            flag++;
            sscanf(line,"%*s %d %d %d",&TotalMem,&TotalUsed,&TotalFree);
        }
        pclose(fp);

        if(flag)
            printf("TotalMem:%d -- TotalUsed:%d -- TotalFree:%dn",TotalMem,TotalUsed,TotalFree);
        else
            printf("not foundn");

    }

    return 0;
}

#ifdef _WIN32
#include <windows.h>
#include <stdio.h>
#include <tchar.h>

#define DIV 1048576 
#define WIDTH 7
#endif

#ifdef linux
#include <unistd.h>
#include <stdlib.h>
#include <stdio.h>
#include <string.h>
#endif


int main(int argc,char *argv[]) 
{
#ifdef _WIN32
MEMORYSTATUSEX statex;
    statex.dwLength = sizeof (statex);
    GlobalMemoryStatusEx (&statex);

    _tprintf (TEXT("There is  %*ld %% of memory in use.n"),statex.dwMemoryLoad);
#endif

#ifdef linux
char cmd[30];
int flag = 0;   
FILE *fp;
char line[130];     
int TotalMem,TotalFree,TotalUsed;

flag=0;
memcpy (cmd,30);
sprintf(cmd,"free -t -m|grep Total");          
fp = popen(cmd,"r");       
while ( fgets( line,fp))
{   
    flag++;
    sscanf(line,&TotalFree);
}
pclose(fp); 

if(flag)
    printf("TotalMem:%d -- TotalUsed:%d -- TotalFree:%dn",TotalFree);
else 
    printf("not foundn");
#endif

    return 0;
}