clamping unsigned ints

Asked Dec 04 '12 at 05:24

Active Dec 28 '12 at 00:47

Viewed 1,026 times

What is the correct way to clamp unsigned ints?

For example, say I have:

 unsigned int ui = 5U;

Now I want to subtract a value from it:

ui = Clamp(ui - MAGIC_VALUE, 0, 255);

I would like ui to contain 0 if MAGIC_VALUE >= 5.

However, I can't just subtract MAGIC_VALUE as the expression ui - MAGIC_VALUE will wrap around to UINT_MAX if MAGIC_VALUE > 5 and end up being clamped to the upper limit, 255. That's the opposite of what I want!

Is there any trick to deal with this?

asked Dec 04 '12 at 05:24

user987280

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`ui = Clamp((int)ui - MAGIC_VALUE, 0, 255);` ? – Karthik T Dec 04 '12 at 05:25
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`ui = (ui > MAGIC_VALUE) ? Clamp(ui - MAGIC_VALUE, 0, 255) : 0;`? – Jonathan Leffler Dec 04 '12 at 05:30

clamping unsigned ints

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