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Author Topic: directive #if and operator sizeof  (Read 4162 times)

andi.martin

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directive #if and operator sizeof
« on: December 17, 2008, 07:26:36 PM »
Hi,

AFAIK the sizeof operator returns a constant expression (integer type).
So why
#if sizeof(char)==1
emits a compiler error..?

Regards,
Andreas Martin
« Last Edit: December 17, 2008, 10:05:59 PM by andi.martin »
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JohnF

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Re: directive #if and operator sizeof
« Reply #1 on: December 18, 2008, 08:38:41 AM »
Quote from: andi.martin on December 17, 2008, 07:26:36 PM
Hi,

AFAIK the sizeof operator returns a constant expression (integer type).
So why
#if sizeof(char)==1
emits a compiler error..?

Regards,
Andreas Martin

I would imagine that using it in a pre-processing context is disallowed.

John
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pgoh

  • Guest
Re: directive #if and operator sizeof
« Reply #2 on: December 18, 2008, 08:06:51 PM »
John is correct. sizeof is evaluated at compile time, while the preprocessor is evaluated before compilation.
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