[[escafandra]]

Dos funciones en C:

__int64 GetFileSize(char *FileName)
{
   WIN32_FIND_DATA Data;
   HANDLE hFile = ::FindFirstFile(FileName, &Data);
   if(hFile==(HANDLE)-1) return 0;
   __int64 S = Data.nFileSizeHigh;
   S = (S << 32) | Data.nFileSizeLow;
   FindClose(hFile);
   return S;
}

//-----------------------------------------------------------------------
__int64 _GetFileSize(char *FileName)
{
   int hFile= _lopen(FileName, 0);
   __int64 S;
   if (!GetFileSizeEx((HANDLE)hFile, (PLARGE_INTEGER)&S)) S=0;
   _lclose(hFile);
   return S;
}

Saludos.