round, roundf, roundl

Rounds a floating-point value to the nearest integer.

double round( 
   double x 
);
float round(
   float x
);  // C++ only
long double round(
   long double x
);  // C++ only
float roundf(
   float x
);
long double roundl(
   long double x
);

Parameters

• x
  The floating-point value to round.

Return Value

The round functions return a floating-point value that represents the nearest integer to x. Halfway values are rounded away from zero, regardless of the setting of the floating-point rounding mode. There is no error return.

Remarks

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

Requirements

For additional compatibility information, see Compatibility.

Example

// crt_round.c
// Build with: cl /W3 /Tc crt_round.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("round(%f) is %.0f\n", x, round(x));
   printf("round(%f) is %.0f\n", -x, round(-x));
   printf("roundf(%f) is %.0f\n", y, roundf(y));
   printf("roundf(%f) is %.0f\n", -y, roundf(-y));
   printf("roundl(%Lf) is %.0Lf\n", z, roundl(z));
   printf("roundl(%Lf) is %.0Lf\n", -z, roundl(-z));
}

round(2.499999) is 2
round(-2.499999) is -2
roundf(2.800000) is 3
roundf(-2.800000) is -3
roundl(2.500000) is 3
roundl(-2.500000) is -3

.NET Framework Equivalent

System::Math::Round

See Also

Reference

Floating-Point Support

ceil, ceilf, ceill

floor, floorf, floorl

fmod, fmodf

lround, lroundf, lroundl, llround, llroundf, llroundl

rint, rintf, rintl

Other Resources

lrint

nearbyint