Question

How to use nearbyint() function to round floating-point to integer in floating-point format in C

Answer 1

#include <stdio.h>     
#include <math.h> 
#include <fenv.h>
 
int main(int argc, char **argv)
{   
	fesetround(FE_TONEAREST); 
    printf("rounding to nearest :\n");
    printf("nearbyint(3.3) = %f\n", nearbyint(3.3));
    printf("nearbyint(3.5) = %f\n", nearbyint(3.5));
    printf("nearbyint(4.5) = %f\n", nearbyint(4.5));    
    printf("nearbyint(4.6) = %f\n", nearbyint(4.6));
    printf("nearbyint(-3.3) = %f\n", nearbyint(-3.3));
    printf("nearbyint(-3.5) = %f\n", nearbyint(-3.5));
    printf("nearbyint(-4.5) = %f\n", nearbyint(-4.5));    
    printf("nearbyint(-4.6) = %f\n\n", nearbyint(-4.6));
      
    fesetround(FE_DOWNWARD);
    printf("rounding down: \n");
    printf("nearbyint(3.3) = %f\n", nearbyint(3.3));
    printf("nearbyint(3.5) = %f\n", nearbyint(3.5));
    printf("nearbyint(4.5) = %f\n", nearbyint(4.5));    
    printf("nearbyint(4.6) = %f\n", nearbyint(4.6));
    printf("nearbyint(-3.3) = %f\n", nearbyint(-3.3));
    printf("nearbyint(-3.5) = %f\n", nearbyint(-3.5));
    printf("nearbyint(-4.5) = %f\n", nearbyint(-4.5));    
    printf("nearbyint(-4.6) = %f\n\n", nearbyint(-4.6));
      
    fesetround(FE_UPWARD);
    printf("rounding up: \n");
    printf("nearbyint(3.3) = %f\n", nearbyint(3.3));
    printf("nearbyint(3.5) = %f\n", nearbyint(3.5));
    printf("nearbyint(4.5) = %f\n", nearbyint(4.5));    
    printf("nearbyint(4.6) = %f\n", nearbyint(4.6));
    printf("nearbyint(-3.3) = %f\n", nearbyint(-3.3));
    printf("nearbyint(-3.5) = %f\n", nearbyint(-3.5));
    printf("nearbyint(-4.5) = %f\n", nearbyint(-4.5));    
    printf("nearbyint(-4.6) = %f\n\n", nearbyint(-4.6));
      
    fesetround(FE_TOWARDZERO);
    printf("rounding toward zero: \n");
    printf("nearbyint(3.3) = %f\n", nearbyint(3.3));
    printf("nearbyint(3.5) = %f\n", nearbyint(3.5));
    printf("nearbyint(4.5) = %f\n", nearbyint(4.5));    
    printf("nearbyint(4.6) = %f\n", nearbyint(4.6));
    printf("nearbyint(-3.3) = %f\n", nearbyint(-3.3));
    printf("nearbyint(-3.5) = %f\n", nearbyint(-3.5));
    printf("nearbyint(-4.5) = %f\n", nearbyint(-4.5));    
    printf("nearbyint(-4.6) = %f\n\n", nearbyint(-4.6));
  
    return 0;
}
 
 
/*
run:
   
rounding to nearest :
nearbyint(3.3) = 3.000000
nearbyint(3.5) = 4.000000
nearbyint(4.5) = 4.000000
nearbyint(4.6) = 5.000000
nearbyint(-3.3) = -3.000000
nearbyint(-3.5) = -4.000000
nearbyint(-4.5) = -4.000000
nearbyint(-4.6) = -5.000000

rounding down:
nearbyint(3.3) = 3.000000
nearbyint(3.5) = 3.000000
nearbyint(4.5) = 4.000000
nearbyint(4.6) = 4.000000
nearbyint(-3.3) = -4.000000
nearbyint(-3.5) = -4.000000
nearbyint(-4.5) = -5.000000
nearbyint(-4.6) = -5.000000

rounding up:
nearbyint(3.3) = 4.000000
nearbyint(3.5) = 4.000000
nearbyint(4.5) = 5.000000
nearbyint(4.6) = 5.000000
nearbyint(-3.3) = -3.000000
nearbyint(-3.5) = -3.000000
nearbyint(-4.5) = -4.000000
nearbyint(-4.6) = -4.000000

rounding toward zero:
nearbyint(3.3) = 3.000000
nearbyint(3.5) = 3.000000
nearbyint(4.5) = 4.000000
nearbyint(4.6) = 4.000000
nearbyint(-3.3) = -3.000000
nearbyint(-3.5) = -3.000000
nearbyint(-4.5) = -4.000000
nearbyint(-4.6) = -4.000000

*/

 

70+ SQL courses for beginners and professionals