LinuxN00b LinuxN00b - 1 year ago 67
C Question

In C is there a technical reason to not use lowercase macro definitions?

I'm starting to learn C coming from a background in Java & Javascript and I'm wondering if there is a technical reason for the following being considered bad practice or if it's just the way the language evolved?

#define bool char
#define false 0
#define true 1
#define null NULL

Everywhere I look I always see defined variables (if that's the correct word) uppercased and I'm wondering if there is a good technical reason for this convention? I'm sure this must have been asked many times but I can't seem to find an answer.

Answer Source

They're called macros. And yes, by convention they're ALL_UPPERCASE to avoid clashes with normal identifiers, because they're just text replacement and don't follow the normal scoping rules of the language.

Consider the following:

#define foo bar
int foo, bar;  // error: preprocessing turns this into int bar, bar;

To avoid surprises like this (code that isn't what it seems like), we try to keep macros distinct.

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