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rint, rintf, rintl


The latest version of this topic can be found at rint, rintf, rintl.

Rounds a floating-point value to the nearest integer in floating-point format.

double rint( double x );  
float rint( float x );  // C++ only  
long double rint( long double x );  // C++ only  
float rintf( float x );   
long double rintl( long double x );  


The floating-point value to round.

The rint functions return a floating-point value that represents the nearest integer to x. Halfway values are rounded according to the current setting of the floating-point rounding mode, the same as the nearbyint functions. Unlike the nearbyint functions, the rint functions may raise the FE_INEXACT floating-point exception if the result differs in value from the argument. There is no error return.

InputSEH Exception_matherr Exception
± ∞, QNAN, INDnonenone

Because C++ allows overloading, you can call overloads of rint that take and return float and long double values. In a C program, rint always takes and returns a double.

FunctionC headerC++ header
rint, rintf, rintl<math.h><cmath>

For additional compatibility information, see Compatibility.

// crt_rint.c  
// Build with: cl /W3 /Tc crt_rint.c  
// This example displays the rounded results of  
// the floating-point values 2.499999, -2.499999,   
// 2.8, -2.8, 2.5 and -2.5.  
#include <math.h>  
#include <stdio.h>  
int main( void )  
   double x = 2.499999;  
   float y = 2.8f;  
   long double z = 2.5;  
   printf("rint(%f) is %.0f\n", x, rint (x));  
   printf("rint(%f) is %.0f\n", -x, rint (-x));  
   printf("rintf(%f) is %.0f\n", y, rintf(y));  
   printf("rintf(%f) is %.0f\n", -y, rintf(-y));  
   printf("rintl(%Lf) is %.0Lf\n", z, rintl(z));  
   printf("rintl(%Lf) is %.0Lf\n", -z, rintl(-z));  

rint(2.499999) is 2  
rint(-2.499999) is -2  
rintf(2.800000) is 3  
rintf(-2.800000) is -3  
rintl(2.500000) is 3  
rintl(-2.500000) is -3  


Floating-Point Support
ceil, ceilf, ceill
floor, floorf, floorl
fmod, fmodf
lrint, lrintf, lrintl, llrint, llrintf, llrintl
lround, lroundf, lroundl, llround, llroundf, llroundl
nearbyint, nearbyintf, nearbyintl