Standard function problems with gcc

lgi123 · 06-22-2006, 07:50 AM

I have problems using standard functions like floor() and ceil() with gcc.

For example, I get: /tmp/ccMNi7Hj.o: In function `main':floor.c

.text+0x21): undefined reference to `floor'
collect2: ld returned 1 exit status

when trying to build this:

Code:

#include <stdio.h>
#include <math.h>

int main(void)
{
        double d = 12.3;
        d = floor(d);
        printf("%f\n", d);

        return 0;
}

However, this works fine:

Code:

#include <stdio.h>
#include <math.h>

int main(void)
{
        printf("%f\n", floor(12.3));

        return 0;
}

But I have no problems with any of this when using Dev-C++ under Windows XP. Does something have to be done differently with gcc under Linux or do I have a bad configuration/libraries?

Flesym · 06-22-2006, 08:13 AM

You have to link against libm.a Thus compile with:

Code:

gcc filename -lm

lgi123 · 06-23-2006, 03:17 PM

Quote:

Originally Posted by Flesym

You have to link against libm.a Thus compile with:

Code:

gcc filename -lm

Thanks, Now it works!