Re: [lwip-users] Stats and code readability

[Zschocke, Florian]

Ed Sutter wrote on Mittwoch, 18. Juni 2003 15:16:

> #define MACRO_XYX(var)        do{++var;}while(0)
> 
> My question is...
> Why do that instead of just doing...
> 
> #define MACRO_XYZ(var)        ++var

In this case you're probably right. It's important with multi-expression
macros, and I just do it with single expression macros out of a habit. A
good compiler optimizes the loop away. I don't know if a case could be
constructed where the single-expression macro could cause trouble. The
general problem and where this do{}whlie(0) construct comes from is
explained here:

http://gcc.gnu.org/onlinedocs/cpp/Swallowing-the-Semicolon.html#Swallowing%2
0the%20Semicolon

Florian.