Date: Mon, 11 Sep 2006 17:57:26 +0530 From: "Amarendra Godbole" <amarendra.godbole@gmail.com> To: freebsd-questions@freebsd.org Subject: Sequence of execution of getopt() and usage()... Message-ID: <294439d20609110527m2093cde8r4a93e391826f2b17@mail.gmail.com>
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Hi,
This is a general FreeBSD source related question, and I am posting it
here, as it did not fit in any other FreeBSD lists...
While browsing through sources for different userland utilities (cat,
chmod, and so on), I noticed that in main(), first getopt() is called
in a while loop, and then the check for the number of arguments passed
is done. Something like this (from chmod.c):
int
main(int argc, char *argv[])
{
...
while ((ch = getopt(argc, argv, "HLPRXfghorstuvwx")) != -1)
...
if (argc < 2)
usage();
...
}
Can't we check for the number of arguments *before* calling getopt()?
Something like:
int
main(int argc, char *argv[])
{
...
if (argc < 2)
usage();
...
while ((ch = getopt(argc, argv, "HLPRXfghorstuvwx")) != -1)
...
}
This might make it a bit more efficient, though I don't have numbers'
to prove this.
I observe a similar pattern in other utilities too - which might mean
that there was a sound reason as to why it was done this way. Can
someone be kind enough to explain this? Thanks in advance!
Best,
Amarendra
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