lround-lroundf-lroundl-llround-llroundf-llroundl.md

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lround, lroundf, lroundl, llround, llroundf, llroundl	API reference for lround, lroundf, lroundl, llround, llroundf, and llroundl; which rounds a floating-point value to the nearest integer.	9/1/2020	llround llroundf llroundl lroundf lround lroundl _o_llround _o_llroundf _o_llroundl _o_lround _o_lroundf _o_lroundl	msvcrt.dll msvcr80.dll msvcr90.dll msvcr100.dll msvcr100_clr0400.dll msvcr110.dll msvcr110_clr0400.dll msvcr120.dll msvcr120_clr0400.dll ucrtbase.dll api-ms-win-crt-math-l1-1-0.dll	DLLExport	apiref	lround lroundl llroundl llround lroundf llroundf	lround function llroundl function llround function lroundf function llroundf function lroundl function	cfb88a35-54c6-469f-85af-f7d695dcfdd8

lround, lroundf, lroundl, llround, llroundf, llroundl

Rounds a floating-point value to the nearest integer.

Syntax

long lround(
   double x
);
long lround(
   float x
);  // C++ only
long lround(
   long double x
);  // C++ only
long lroundf(
   float x
);
long lroundl(
   long double x
);
long long llround(
   double x
);
long long llround(
   float x
);  // C++ only
long long llround(
   long double x
);  // C++ only
long long llroundf(
   float x
);
long long llroundl(
   long double x
);
#define lround(X) // Requires C11 or higher

Parameters

x
The floating-point value to round.

Return value

The lround and llround functions return the nearest long or long long integer to x. Halfway values are rounded away from zero, regardless of the setting of the floating-point rounding mode. There's no error return.

Input	SEH exception	_matherr exception
± QNaN, IND	none	_DOMAIN

Remarks

Because C++ allows overloading, you can call lround or llround overloads 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, lround and llround always take and return a double.

If you use the <tgmath.h> lround() 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.

Requirements

Routine	Required header
lround, lroundf, lroundl, llround, llroundf, llroundl	<math.h>
lround macro	<tgmath.h>

For more compatibility information, see Compatibility.

Example

// crt_lround.c
// Build with: cl /W4 /Tc crt_lround.c
// This example displays the rounded results of
// the floating-point values 2.499999, -2.499999,
// 2.8, -2.8, 3.5 and -3.5.

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

int main( void )
{
   double x = 2.499999;
   float y = 2.8f;
   long double z = 3.5L;

   printf("lround(%f) is %d\n", x, lround(x));
   printf("lround(%f) is %d\n", -x, lround(-x));
   printf("lroundf(%f) is %d\n", y, lroundf(y));
   printf("lroundf(%f) is %d\n", -y, lroundf(-y));
   printf("lroundl(%Lf) is %d\n", z, lroundl(z));
   printf("lroundl(%Lf) is %d\n", -z, lroundl(-z));
}

lround(2.499999) is 2
lround(-2.499999) is -2
lroundf(2.800000) is 3
lroundf(-2.800000) is -3
lroundl(3.500000) is 4
lroundl(-3.500000) is -4

See also

Math and floating-point support
ceil, ceilf, ceill
floor, floorf, floorl
fmod, fmodf
lrint, lrintf, lrintl, llrint, llrintf, llrintl
round, roundf, roundl
nearbyint, nearbyintf, nearbyintl
rint, rintf, rintl