* math.h - exp
@ 2003-09-04 3:51 didier
2003-09-04 9:50 ` Claudio Bley
0 siblings, 1 reply; 2+ messages in thread
From: didier @ 2003-09-04 3:51 UTC (permalink / raw)
To: gcc-help
I have installed gcc 3.3.1 on a PC-linux system, with bootstrap by gcc
2.96. Every thing was right. But in a test program, the calll of the
"exp" function generated an error message " undefined reference to
'exp', thought I include the file <math.h>. What is the reason ?
Thanks
Didier
^ permalink raw reply [flat|nested] 2+ messages in thread
* Re: math.h - exp
2003-09-04 3:51 math.h - exp didier
@ 2003-09-04 9:50 ` Claudio Bley
0 siblings, 0 replies; 2+ messages in thread
From: Claudio Bley @ 2003-09-04 9:50 UTC (permalink / raw)
To: gcc-help
On Thu, Sep 04, 2003 at 05:53:54AM +0200, didier wrote:
> I have installed gcc 3.3.1 on a PC-linux system, with bootstrap by gcc
> 2.96. Every thing was right. But in a test program, the calll of the
> "exp" function generated an error message " undefined reference to
> 'exp', thought I include the file <math.h>. What is the reason ?
Including a header file usually is not enough as it usually only
contains function declarations / prototypes. You need to link with the
math library `libm' which provides the compiled code for the various
math functions such as `exp':
gcc prog.c -lm
--
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2003-09-04 3:51 math.h - exp didier
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