Dealing with 64-bit numbers 32-bit stylee

Hello,

I'm trying to write a program that will profile my hard drive. I know my Program Files directory at least is over 4GB, so is this code, which uses FindFile, right?:-

Code:

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// If adding the low DWORD to our count tips the scales...
if (wfd.nFileSizeLow > (0xFFFFFFFF - ulSize))
{
        (*lpDirSizeHigh)++;
        wfd.nFileSizeLow -= 0xFFFFFFFF - ulSize;
        ulSize = 0;
}

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