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clock_t & return -1
- From: "Alex Vinokur" <alexvn at connect dot to>
- To: cygwin at cygwin dot com
- Date: Tue, 14 Oct 2003 19:31:45 +0200
- Subject: clock_t & return -1
# ------ man clock (fragments) ------
# NAME
# `clock'--cumulative processor time
#
#
# SYNOPSIS
# include <time.h>
# clock_t clock(void);
#
# RETURNS
# The amount of processor time used so far by your program, in units
# defined by the machine-dependent macro `CLOCKS_PER_SEC'.
# If no measurement is available, the result is `-1'.
#
# -----------------------------------
------ C code : File t.c ------
#include <time.h>
int main()
{
return (!(clock () == -1));
}
-------------------------------
------ Compilation ------
$ gcc -W -Wall t.c
t.c: In function `main':
t.c:4: warning: comparison between signed and unsigned
-------------------------
So, clock() is unsigned and never returns -1 (?!)
If one must write
----------------------------------
if (!(clock () == (clock_t)(-1)));
----------------------------------
I think it is worth noting that in the manual.
--
=====================================
Alex Vinokur
mailto:alexvn@connect.to
http://mathforum.org/library/view/10978.html
news://news.gmane.org/gmane.comp.lang.c++.perfometer
=====================================
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