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.
Input |
SEH Exception |
Matherr Exception |
|---|---|---|
± QNAN,IND |
none |
_DOMAIN |
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
Routine |
Required header |
|---|---|
round, roundf, roundl |
<math.h> |
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
See Also
Reference
lround, lroundf, lroundl, llround, llroundf, llroundl