more questions about efficient C code

[Martin Minow]

The question was asked whether the common C idiom
	if ((fp = fopen("foo.bar", "r")) == NULL) { ...
really is more efficient than
	fp = fopen("foo.bar", "r");
	if (fp == NULL) { ...

In response, Joe Durnavich makes the good point that the saving
of one measly move instruction (which a good compiler would
optimize out anyway) isn't worth the effort.

In response, I would again point out that this is a C idiom --
one of the habits a programmer picks up for better or worse.
In defense, I would note that writing this as a single statement
ties (visually) the if condition closer to the fopen() result that
is being tested than would be the case were one to write two
statements.

Martin Minow
decvax!minow