вот так пральней


LPCSTR ReadFromFile(LPVOID Buff)
{
HANDLE FileHandle;
DWORD R;
DWORD Size;

FileHandle = CreateFileA("C:\\sys.txt",GENERIC_READ,FILE_SHARE_ READ,NULL,OPEN_EXISTING,FILE_ATTRIBUTE_NORMAL,NULL );
Size = GetFileSize(FileHandle, &Size);
if(Size>255) Size=255;
ReadFile(FileHandle, Buff, Size, &R, NULL);
*(Line+R)=0;
CloseHandle(FileHandle);
return 0;
}



int APIENTRY WinMain(HINSTANCE hInstance, HINSTANCE hPrevInstance, LPSTR lpCmdLine, int nCmdShow)
{
char Line[256];
ReadFromFile(Line);
MessageBox(0,Line,"",0);

}