"str*cmp()" ain't Boolean (was Re: v18i058: mush - Mail User's Shell, Part01/22)

[Bill Carpenter]

guy> Perhaps this is a hint that one shouldn't treat "strncmp()" as if
guy> it were a Boolean function, and should instead compare its result
guy> with 0 explicitly, e.g. if you're comparing strings for equality,
guy> use "=="?

Since most of the time I'm using str*cmp() in a Boolean way anyhow,
and since I used to frequently get the sense of the test reversed, I
almost always do it as a macro now:

 #define EQSTR(a,b)    ((a) && (b) && (*(a) == *(b)) && !strcmp((a),(b)))
 #define EQSTRN(a,b,n) ((a) && (b) && (*(a) == *(b)) && !strncmp((a),(b),(n)))

Of course, these are a little elaborate and have side-effects, so you
could stick with the simpler

 #define EQSTR(a,b)    (!strcmp((a),(b)))
 #define EQSTRN(a,b,n) (!strncmp((a),(b),(n)))

(especially if you enjoy dereferenced nulls as much as I do :-).
-- 
  Bill Carpenter         att!hos1cad!wjc  or  attmail!bill