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

int main() {

  float f;
  int   i;

  f = 12.0;
  for ( i=0; i<10; i++ ) {
    printf( "f=%4.1f ceil(%4.1f)=%4.1f floor(%4.1f)=%4.1f floor(%4.1f+0.5)=%4.1f ceil(%4.1f+0.5)=%4.1f\n",
	    f, f,ceil(f), f,floor(f), 
	    f,floor(f+0.5), f,ceil(f+0.5) );
    f += .1;
  }

} /* end of main() */


/* output:
f=12.0 ceil(12.0)=12.0 floor(12.0)=12.0 floor(12.0+0.5)=12.0 ceil(12.0+0.5)=13.0
f=12.1 ceil(12.1)=13.0 floor(12.1)=12.0 floor(12.1+0.5)=12.0 ceil(12.1+0.5)=13.0
f=12.2 ceil(12.2)=13.0 floor(12.2)=12.0 floor(12.2+0.5)=12.0 ceil(12.2+0.5)=13.0
f=12.3 ceil(12.3)=13.0 floor(12.3)=12.0 floor(12.3+0.5)=12.0 ceil(12.3+0.5)=13.0
f=12.4 ceil(12.4)=13.0 floor(12.4)=12.0 floor(12.4+0.5)=12.0 ceil(12.4+0.5)=13.0
f=12.5 ceil(12.5)=13.0 floor(12.5)=12.0 floor(12.5+0.5)=13.0 ceil(12.5+0.5)=14.0
f=12.6 ceil(12.6)=13.0 floor(12.6)=12.0 floor(12.6+0.5)=13.0 ceil(12.6+0.5)=14.0
f=12.7 ceil(12.7)=13.0 floor(12.7)=12.0 floor(12.7+0.5)=13.0 ceil(12.7+0.5)=14.0
f=12.8 ceil(12.8)=13.0 floor(12.8)=12.0 floor(12.8+0.5)=13.0 ceil(12.8+0.5)=14.0
f=12.9 ceil(12.9)=13.0 floor(12.9)=12.0 floor(12.9+0.5)=13.0 ceil(12.9+0.5)=14.0

 */