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Asked: 2026-05-11T05:33:35+00:00

Lets say I have some raster data I want to write to a file..

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Lets say I have some raster data I want to write to a file.. Now I want to write it as a bmp file..

This data happens to be not DWORD aligned, which, if I understand correctly, needs to be padded with enough bytes to reach the next DWORD..

However, when I try to pad it with this code:

bmFile.Write(0x0, (4-(actualWidth%4)));

I get an error.. If I try to debug (I’m using MSVC++ 6.0), the next statement points to an ASSERT in CFile::Write that asserts the first parameter is NULL.. So this fails..

How should I pad it? should I write out:

bmFile.Write('0x0'(4-(actualWidth%4)));

instead? or would this be treated literally…?

Thanks..

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1 Answer

  1. Perhaps try:

    bmFile.Write('\0\0\0\0', (4-(actualWidth%4)));

    Your first example is, as you say, trying to write data pointed to by a null pointer. Your second example would write from the bytes ‘0’, ‘x’, ‘0’ which have ASCII values 0x30, 0x78, 0x30, which is probably not what you intend.

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