What is strdup() supposed to do? Does anyone have a copy?

[Jonathan I. Kamens]

(Note the Followup-To.)

In article <1991Feb19.004526.16033 at onion.rain.com> jeff at onion.rain.com (Jeff Beadles) writes:

    In <1991Feb18.154159.430 at persoft.com> dag at persoft.com (Daniel Glasser) writes:
    > [he asks why the temporary char *ret inside strdup is declared static]

   A creature of habit, I suppose.  I've been bitten too often when I return
   something from a function that isn't static.  (int's, for example.)  For this
   case, it really doesn't matter.

I would suggest that if you can't tell the difference between a value
that is safe to return from a function, and a value that is not,
you're better off letting other people post code to the net.  I posted
a working version of strdup() the same day the question was asked, and
yet we have all these people posting inferior versions (That's not my
ego speaking, for all of you who are getting ready to pounce on your
"F" key for flaming me about saying, "My code is better than yours!"
That's just simple fact.  The version I posted had no errors; if you
think it did, feel free to point them out.).

Yes, I know there are lags in news transmission, and it's quite
possible that you didn't see my posting before posting yours.  I
wouldn't be mentioning the duplication at all if it weren't for the
fact that your code was wrong.

You should not declare variables static when they don't have to be
static.  Code which declares a variable static when that variable has
absolutely no reason whatsover to be static is wrong.

   It's kinda like the braces around the malloc failure.  They're not technically
   required, but it's not a bad habit. :-)

Braces around a one-line "if" block are good programming because they
don't affect the compiled code, and because they will save you from
problems if you change things later so that there is more than one
statement in the body of the "if," and because if the statement is
actually a macro that has multiple statements in it, the braces
protect you from any dangerous results.

On the other hand, declaring a variable static when it doesn't have to
be *does* affect the compiler output, by keeping a variable in memory
all the time when it doesn't have to be.  Furthermore, unless you plan
to seriously change the functionality of strdup() at some point in the
future, there is no chance that that variable will ever need to be
static, so there is no "preventative" excuse to make it static.

    >Nit #2:	You should simplify your expression in the "malloc()", that is,
    >		sizeof(char) * strlen(foo) + sizeof(char)
    >	could be written
    >		sizeof(char) * (strlen(foo) + 1)

   Untrue.  What if sizeof(char) != 1?  Yours will break, and mine will work.

You're wrong.  Both expressions above will result in the proper value,
whether sizeof(char) is 1 or not.  Your expression takes the number of
characters in the string, multiplies it by the size of a character,
and adds the size of a character.  The other suggested expression
takes the number of characters in the string, adds 1 to it, and
multiples the result by the size of a character.  The fact that these
will result in the same value should be obvious.  And, incidentally, I
agree with the previous poster that the latter expression is clearer
than the former.

I'm sorry if I'm coming down a bit hard on you.  I guess I'm taking
out on you all the frustration I've been feeling for the past three
days, watching people post wrong or incomplete answers to a solved
problem with the solution has already been posted.  It's a bit
irritating.

Jonathan Kamens			              USnail:
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