不知楼主解决了没有！
按楼主要求给出一个参考答案，希望楼主领略其中之意。

#pragma code ("kernel32.dll")
VOID GetLocalTime(LPSYSTEMTIME lpSystemTime);
BOOL CreateDirectoryA(LPCTSTR lpFileName,LPSECURITY_ATTRIBUTES lpSecurityAttributes);
#pragma code ()

char szDir[255]="D:\\生产报表\\";//建立的文件夹的路径

char szDir2[255]="";

HWND hwnd=NULL;

int iRet;

BOOL fbRet=FALSE;

BOOL fbRet2=FALSE;

SYSTEMTIME sysTime;

GetLocalTime(&sysTime);

sprintf(szDir2,"D:\\生产报表\\%d-%d-%d\\",sysTime.wYear,sysTime.wMonth,sysTime.wDay);

hwnd=FindWindow(NULL,"WinCC-运行系统 - ");

fbRet=CreateDirectoryA(szDir,NULL);

if (!fbRet)
{
iRet=MessageBox(hwnd,"生产报表文件夹已经创建了！","对话框",MB_OKMB_ICONQUESTIONMB_SYSTEMMODAL);
}
else
{
iRet=MessageBox(hwnd,"生产报表文件夹创建成功！","对话框",MB_OKMB_ICONQUESTIONMB_SYSTEMMODAL);
}

fbRet2=CreateDirectoryA(szDir2,NULL);

if (!fbRet2)
{
iRet=MessageBox(hwnd,"日期报表文件夹已经存在！","对话框",MB_OKMB_ICONQUESTIONMB_SYSTEMMODAL);
}
else
{
iRet=MessageBox(hwnd,"日期报表文件夹创建成功！","对话框",MB_OKMB_ICONQUESTIONMB_SYSTEMMODAL);
}

注意路径分隔符为"\\" ！！！