Thread: Round() Function

Hi All,
I am trying to use round() function but gcc couldn't find it...
Can you please help me??

Compiler: gcc 4.1.2
Command: gcc round_func.c

Code:

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

int main(void)
{
  double a = 13.05;    
  printf("round of  %.1lf is  %.1lf\n", a, round(a));
  return 0;
}

Error Message:
round_func.c:7: warning: incompatible implicit declaration of built-in function ‘round’
/tmp/cckuuW3l.o: In function `main':
round_func.c.text+0x24): undefined reference to `round'


Thanks and Regrads,
Dharak

Because there's no such a function. Use floor() or ceil() instead.

Originally Posted by DRK

Because there's no such a function. Use floor() or ceil() instead.

Code:

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

    int main()
    {
          double a, b, c ;
          a = 3.8;
          b = floor(a);  //Not Working
          c = floor(104.54) //Working
        printf ("Floor of %0lf is %01f\n", a, c);
        return 0;
    }

Here if I pass constant value in floor function, then its working but if I pass variable then it is not working.

any idea?

Do I need to include something else also?

Thanks and Regards,
Dharak

I also dont understand, gcc version is 4.1.2

Originally Posted by ZuK

You should output

Code:

printf ("Floor of %0lf is %01f\n", b, c); // a is not rounded

Kurt

That's not a issue. If you remove print statement then also it won't work with variable.

Code:

#include<stdio.h>
#include<math.h>
 
int main()
{
      double a, b, c ;
      a = 3.8d;
      b = floor(a);  //Not Working
      c = floor(104.54); //Working
    printf ("Floor of %0lf is %0lf\n", a, b);
    return 0;
}

my output

Code:

Floor of 3.800000 is 3.000000

Your posted code doesn't even compile because you are missing a semicolon on line 9.

And we can't help you if you don't tell us what doesn't work. When I run a corrected version of your code, everything works as expected.

So what's your problem?

Bye, Andreas

My Program is:

Code:

#include<stdio.h>
#include<math.h>
  
int main()
{
      double a, b;
      a = 3.8;
      b = floor(a); 
    printf ("Floor of %0lf is %0lf\n", a, b);
    return 0;
}

and now output is

Code:

[sdharak@Quartz Final]$ gcc round_func.c
/tmp/ccl2Wy6h.o: In function `main':
round_func.c:(.text+0x24): undefined reference to `floor'
collect2: ld returned 1 exit status

gcc version is
gcc -dumpversion
4.1.2

Now I dont understand what is the issue with my setup?
It should work..


Thanks,
Dharak

Originally Posted by laserlight

You probably need to explicitly link to the math library with the -lm option.

Ohhhh...
It's working... Thanks....
But why I need to do this?
Is there any issue with gcc version??

-Dharak