lround(), lroundf(), lroundl()
QNX SDP8.0C Library ReferenceAPIDeveloper
Round a floating-point number to the nearest integer value
Synopsis:
#include <math.h>
long int lround( double x );
long int lroundf( float x );
long int lroundl( long double x );
Arguments:
- x
- The number that you want to round.
Library:
- libm
- The general-purpose math library.
- libm-sve
- A library that optimizes the code for ARMv8.2 chips that have Scalable Vector Extension hardware.
Your system requirements will determine how you should work with these libraries:
- If you want only selected processes to run with the SVE version, you can include both libraries in your OS image and use the -l m or -l m-sve option to qcc to link explicitly against the appropriate one.
- If you want all processes to use the SVE version, include libm-sve.so in your OS image and set up a symbolic link from libm.so to libm-sve.so. Use the -l m option to qcc to link against the library.
Note:
Compile your program with the -fno-builtin option to prevent the compiler from using a
built-in version of the function.
Description:
The lround(), lroundf(), and lroundl() functions round a floating-point number to the nearest integer value, rounding halfway cases away from zero, regardless of the current rounding direction.
To check for error situations, use feclearexcept() and fetestexcept(). For example:
- Call
feclearexcept(FE_ALL_EXCEPT)before calling lround(), lroundf(), or lroundl(). - On return, if
fetestexcept(FE_ALL_EXCEPT)is nonzero, then an error has occurred.
Returns:
The rounded integer value.
| If: | These functions return: | Errors: |
|---|---|---|
| x is ±Inf | An unspecified value | FE_INVALID |
| x is NaN | An unspecified value | FE_INVALID |
| The correct value is too large to represent as a long | An unspecified value | FE_INVALID |
These functions raise FE_INEXACT if the FPU reports that the result can't be exactly represented as a floating-point number.
Classification:
| Safety: | |
|---|---|
| Cancellation point | No |
| Signal handler | Yes |
| Thread | Yes |
Page updated: