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From: shaw@paralogics.UUCP (Guy Shaw)
Newsgroups: comp.lang.perl
Subject: How about a finicky printf()?
Keywords: printf, format string, bounds checking
Message-ID: <430@paralogics.UUCP>
Date: 23 Jun 91 05:43:26 GMT
Organization: Paralogics; Santa Monica, CA
Lines: 29


How about a finicky printf() ?

The Perl implementation of printf() does not do any checking to ensure that
the number of arguments given matches the number called for in the format
string.  Extra arguments are ignored.  Arguments needed beyond the number
given are silently supplied as though a null value were given.  So, the
argument list is, in effect, padded with null values.

  perl -e 'printf "%d %d\n", 1, 2, 3'        =>  1 2
  perl -e 'printf "%d %d\n", 1'              =>  1 0

Awk complains about this at run-time.  Perl ought to be able to complain
at run-time.  I would like to see Perl do awk one better and do a bit
of compile-time analysis, where possible, as well.  Sure, you couldn't
do that for format strings that are variables, and Perl has things like
eval() that can make things a bit trickier; but the majority of times,
in practice, format strings are constants.

If performance degradation is part of the rationale for not doing this
in Perl, then I would suggest doing the checking only when the -w option
is turned on.

Just Another Perl Suggestion from
Just Another Perl Dilettante,
-- 
Guy Shaw
Paralogics
paralogics!shaw@uunet.uu.net  or  uunet!paralogics!shaw