Macro in a loop?

for(x;x<crap;x++)
{
    macro(x,y);开发者_如何学运维
}

How is this handled by preprocessor? Is this loop unrolled or something else?

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The macro is expanded before the code is compiled - it doesn't matter whether it's in a loop or anywhere else.

#define macro(x, y) doSomething(x, y)
for(x;x<crap;x++){
    macro(x,y);
}

will expand to:

for(x;x<crap;x++){
    doSomething(x,y);
}

The context surrounding macro(x,y) has no effect on how the preprocessor expands it.

(The preprocessor doesn't even know what programming language you're using - it could be C, Python, Brainfuck or a letter to your bank manager and it would expand macros just the same way.)

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#define macros can be thought of as a search and replace before compilation action happens. This means whatever your macro equates to will be directly substituded in its reference inside your code. No, the loop is no unrolled.