Why the trunc function of C shows me an error?

Question

When i tried to run the trunc function in C it gives me an error that says undefined reference to `trunc' how to resolve this error?

the error code is here:

/usr/bin/ld: /tmp/ccTANPox.o: in function `floatmod': temp1.c:(.text+0x3a6): undefined reference to `trunc' collect2: error: ld returned 1 exit status

Answer 1

if I compile code below with gcc main.c, then I see this error (which is similar to yours)

/tmp/ccbouRK0.o: In function `main':
main.c:(.text+0x23): undefined reference to `trunc'
collect2: error: ld returned 1 exit status

and compile works with gcc -lm main.c (where you see how to use -lm).

#include <math.h>
#include <stdio.h>
int main()
{
   double f=9.8;
   int i;
   i=trunc(f);
   printf("%i",i);
   return 0;    
}