lrint(), lrintf(), lrintl() and llrint(), llrintf(), llrintl() — Round the argument to the nearest integer

Standards

Format

#define _ISOC99_SOURCE
#include <math.h>

long int lrint(double x);
long int lrintf(float x);
long int lrintl(long double x);

long long int llrint(double x);
long long int llrintf(float x);
long long int llrintl(long double x);

#define _TR1_C99
#include <math.h>

long int lrint(float x);
long int lrint(long double x);
long long int llrint(float x);
long long int llrint(long double x);

General description

Returned value

If successful, they return the rounded integer value. If the correct value is positive or negative and too large to represent as a long (lrint() family) or long long (llrint() family), a domain error will occur and an unspecified value is returned.

Example

/*
 * This program illustrates the use of lrint() function
 *
 * Note: To get the output shown in this  information, this program 
 *       should be compiled using FLOAT(IEEE)
 *
 */
#define _ISOC99_SOURCE
#include <math.h>
#include <stdio.h>
#include <_Ieee754.h>   /* save/get fpc functions   */

char *RoundStr (_FP_rmode_t rm_type) {
  char *RndStr="undetermined";
   switch (rm_type) {
     case (_RMODE_RN):
        RndStr="round to nearest";
        break;
     case (_RMODE_RZ):
        RndStr="round toward zero";
        break;
     case (_RMODE_RP):
        RndStr="round toward +infinity ";
        break;
     case (_RMODE_RM):
        RndStr="round toward -infinity ";
        break;
   }
   return (RndStr);
}

void main() {

  _FP_fpcreg_t save_rmode, current_rmode;
  long int     rnd2nearest;
  double       number=500.99;

  printf("Illustrates the lrint() function\n");
  __fpc_rd(&current_rmode);     /* get current rounding mode */

  rnd2nearest = lrint(number);
  printf ("When rounding direction is %s:\n lrint(%.2f) = %li\n",
           RoundStr(current_rmode.rmode), number, rnd2nearest);
  save_rmode.rmode = _RMODE_RZ;
  __fpc_sm(save_rmode.rmode);   /* set rounding mode to round to zero */

  rnd2nearest = lrint(number);
  printf ("When rounding direction is %s:\n lrint(%.2f) = %li\n",
           RoundStr(save_rmode.rmode), number, rnd2nearest);
}

Output

Illustrates the lrint() function
When rounding direction is round to nearest:
 lrint(500.99) = 501
When rounding direction is round toward zero:
 lrint(500.99) = 500

Related information

• math.h
• ceil(), ceilf(), ceill() — Round up to integral value
• floor(), floorf(), floorl() — Round down to integral value
• llround(), llroundf(), llroundl() — Round to the nearest integer
• lround(), lroundf(), lroundl() — Round a decimal floating-point number to its nearest integer
• nearbyint(), nearbyintf(), nearbyintl() — Round the argument to the nearest integer
• rint(), rintf(), rintl() — Round to nearest integral value
• round(), roundf(), roundl() — Round to the nearest integer
• trunc(), truncf(), truncl() — Truncate an integer value