C Newbie problems with functions (I think)

Why?

Code:

---


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

int main(void)
{
  float x;

  float round(float number);

  while(1)
      {
        printf("Enter a number");
        scanf("%f", &x);
        printf("round(%f) = %f", x, round(x));
      }

  return 0;
}



float round(float number)
{
  return floor(number +.5);
}

---

gcc ...

Code:

---

05_10.c: In function ‘main’:
05_10.c:8: warning: conflicting types for built-in function ‘round’
/tmp/ccgnH0xg.o: In function `round':
05_10.c:(.text+0x6b): undefined reference to `floor'
collect2: ld returned 1 exit status

---

Thanks in advance

There is a standard function in math.h that takes a double and returns a double, called round. This is what the compiler is moaning about.

man round

If you want to use the functions in math.h, you need to link to libm, so you need -lmon the gcc line.

--
Mats

mmm, maybe I didn't understand something ... this's my new code

Code:

---


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

int main(void)
{
  double x;

  double myround(double number);

  while(1)
      {
        printf("Enter a number");
        scanf("%f", &x);
        printf("myround(%f) = %f", x, myround(x));
      }

  return 0;
}



double myround(double number)
{
  return floor(number +.5);
}

---

Did you mean gcc -lmon asd.c?

Code:

---

$: gcc -lmon asd.c
/usr/bin/ld: cannot find -lmon
collect2: ld returned 1 exit status

---

I use Debian Gnu/linux and Glibc,

Code:

---

$: ls /usr/include/|grep ^math
math.h

---

Sorry, missed a space in the original post: the command should be something like:

Code:

---

gcc -lm blah.c -o blah

---

--
Mats

Ok, it works! :)

thank you again