C++ GetSystemDirectory()

关于GetSystemDirectory function，参考：https://msdn.microsoft.com/en-us/library/windows/desktop/ms724373(v=vs.85).aspx

以下代码摘自Getting System Information（https://msdn.microsoft.com/en-us/library/windows/desktop/ms724426(v=vs.85).aspx）。

IDE: Microsoft Visual Studio Community 2017 15.5.2

操作系统：Windows 7 x64

#include "stdafx.h"    /* IDE自行创建的 */

#include <windows.h>

#define INFO_BUFFER_SIZE 21

int main(int argc, char **argv)
{
    TCHAR infoBuf[INFO_BUFFER_SIZE];
    UINT RetSize;

    RetSize = GetSystemDirectory(infoBuf, INFO_BUFFER_SIZE);
//    RetSize = 0;
    if ((RetSize != 0) && (RetSize <= INFO_BUFFER_SIZE)) {
        // If the function succeeds, the return value is the length, in TCHARs, of the string copied to the buffer,
        // not including the terminating null character.

        // Display the system directory.
        printf("System Directory: %ls", infoBuf);
    }
    else if (RetSize > INFO_BUFFER_SIZE) {
        // If the length is greater than the size of the buffer, 
        // the returnv alue is the size of the buffer required to hold the path, 
        // including the terminating null character.
        printf("The size of the buffer is not enough, need %d TCHARs at least. 
", RetSize);
    }
    else {
        // If the function fails, the return value is zero. To get extended error information, call GetLastError.
        printf("Get system directory failed with error: %d", GetLastError());
    }

    getchar();

    return 0;
}

可以修改INFO_BUFFER_SIZE的值，改变程序的运行结果。

也可以去掉RetSize = 0;前面的注释，模拟错误（实际上不是错误，我只是用来测试if语句的条件）。

不知道是否存在BUG？？？