Le Sunday 04 October 2009 à 00:22:41, vous avez écrit :

Hello: I am new to linux and facing a simple compile problem. I have written a C file which is using the do_gettimeofday() function.

#include <linux/time.h> #include <stdio.h>

main() { struct timeval start;

do_gettimeofday(&start); printf ("%d", start.tv_usec); }

gcc a1.c -- undefined reference to `do_gettimeofday'

here is the PATH:

echo $PATH /usr/lib/qt-3.3/bin:/usr/kerberos/bin:/usr/lib/ccache:/usr/local/bin:/bin:/ usr/bin:/usr/local/sbin:/usr/sbin:/sbin:/homes/iws/arpalla/bin

I checked that the /usr/include/linux/time.h file got the function declaration for do_gettimeofday()

Is there anything missing in the PATH variable?

I am facing same error for rdtscl() function as well!!

The Linux version is :

[arpalla]$ uname -a Linux <..> 2.6.30-2.0 #6 SMP Mon Sep 21 11:03:44 PDT 2009 i686 i686 i386 GNU/Linux

Can anyone please help?

Thanks, Anu

% man gettimeofday NAME gettimeofday, settimeofday - get / set time

SYNOPSIS #include <sys/time.h>

int gettimeofday(struct timeval *tv, struct timezone *tz); int settimeofday(const struct timeval *tvtz);

DESCRIPTION The functions gettimeofday() and settimeofday() can get and set the time as well as a timezone. The tv argument is a struct timeval (as specified in <sys/time.h>):

struct timeval { time_t tv_sec; /* seconds */ suseconds_t tv_usec; /* microseconds */ }; [...]

// getsecond.c #include <sys/time.h> #include <stdio.h>

main(void) {

struct timeval tv; double t = 0.0;

if ( gettimeofday(&tv, NULL) != -1 ) t = tv.tv_usec / 1000000.0 + tv.tv_sec;

printf ("%f\n", t); }

% gcc -O2 -s getsecond.c -o getsecond.bin

% ./getsecond.bin 1254613660.603762

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