Comments on: A little-known trick with C switches

By: Torbjörn Andersson

Torbjörn Andersson — Sat, 07 Mar 2009 19:20:20 +0000

Probably not. At least, I’ve never seen it in any book on standard C. Of course, there could be other compilers that also implement it as an extension.

Of course, you can still do some pretty strange things with switch in standard C. My favorite example (in the “I’m never, ever, EVER going to use that!” sense) is probably Duff’s Device: http://en.wikipedia.org/wiki/Duff%27s_device

By: Ahmed Ibrahim

Ahmed Ibrahim — Sat, 07 Mar 2009 15:08:08 +0000

Do you mean that if i used it in a non-using GCC compiler, it won’t work?

By: Jeff Craig

Jeff Craig — Fri, 06 Mar 2009 20:15:48 +0000

Ah, so this is a GCC extension. A co-worker and I were absolutely amazed that we’d never heard of this before.

By: Torbjörn Andersson

Torbjörn Andersson — Fri, 06 Mar 2009 10:12:47 +0000

It’s one of many GCC extensions to the C/C++ languages. It’s been there for a long time:

http://gcc.gnu.org/onlinedocs/gcc-4.3.3/gcc/C-Extensions.html#C-Extensions

By: Ahmed Ibrahim

Ahmed Ibrahim — Thu, 05 Mar 2009 20:35:51 +0000

WOW! I didnt know that i can do this in a switch statement .

By: Clive Crous

Clive Crous — Wed, 04 Mar 2009 07:59:15 +0000

Ruby also allows this eg:

case number
when 1..4
do_something
when 5..10
do_something_else
when /[A-Za-z ]+/
do_something_alphabetic
else
do_something_defalt
end

By: blindcoder

blindcoder — Tue, 03 Mar 2009 10:46:12 +0000

That’s actually nice to know. Makes for easier-to-read code.

My personal favorite switch statement is Perl, though:

for ($variable){
if (/^abc$/){
do_something();
} elsif (/^[0-9]+$/){
do_something_else();
} else {
throw_an_error();
}
}