When do you use "if ( a = b )"? (was Re: Funny mistake)

[Erik Bergersjo]

In article <65837 at eerie.acsu.Buffalo.EDU> chu at acsu.buffalo.edu (john c chu)
writes:

>[concerning "if ( a = b )"
>
>Is there a good use for this?

There sure is. I can think of two major uses:

(I)	b is a function, perhaps returning a pointer to something
	on success and NULL otherwise.
(II)	b is a hardware register, cleared on reading.

Of course, in both cases "a = b; if( a )..." would do, but if you don't
have a good optimizing compiler the final code might get worse.
Besides, I think "if(a = b)" is more readable. It's clearly one of those
extra features / pecularities that make C the special language it is!

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