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rint, rintf, rintl

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


double rint( double x );
float rintf( float x );
long double rintl( long double x );
#define rint(X) // Requires C11 or higher

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


The floating-point value to round.

Return value

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's no error return.

Input SEH exception _matherr exception
± INF, QNaN, IND none none


Because C++ allows overloading, you can call overloads of rint that take and return float and long double values. In a C program, unless you're using the <tgmath.h> macro to call this function, rint always takes and returns a double.

If you use the <tgmath.h> rint() macro, the type of the argument determines which version of the function is selected. See Type-generic math for details.

By default, this function's global state is scoped to the application. To change this behavior, see Global state in the CRT.


Function C header C++ header
rint, rintf, rintl <math.h> <cmath>
rint macro <tgmath.h>

For more 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

See also

Math and 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