LROUND(3M) Mathematical Library Functions LROUND(3M)

# NAME

lround, lroundf, lroundl - round to nearest integer value

# SYNOPSIS

```c99 [ flag... ] file... -lm [ library... ]
#include <math.h>
long lround(double x);```

`long lroundf(float x);`

`long lroundl(long double x);`

# DESCRIPTION

These functions round their argument to the nearest integer value, rounding halfway cases away from zero, regardless of the current rounding direction.

# RETURN VALUES

Upon successful completion, these functions return the rounded integer value.

If x is NaN, a domain error occurs and an unspecified value is returned.

If x is +Inf, a domain error occurs and an unspecified value is returned.

If x is −Inf, a domain error occurs and an unspecified value is returned.

If the correct value is positive and too large to represent as a long, a domain error occurs and an unspecified value is returned.

If the correct value is negative and too large to represent as a long, a domain error occurs and an unspecified value is returned.

# ERRORS

These functions will fail if:

Domain Error

The x argument is NaN or ±Inf, or the correct value is not representable as an integer.

If the integer expression (math_errhandling & MATH_ERREXCEPT) is non-zero, then the invalid floating-point exception is raised.

# USAGE

An application wanting to check for exceptions should call feclearexcept(FE_ALL_EXCEPT) before calling these functions. On return, if fetestexcept(FE_INVALID | FE_DIVBYZERO | FE_OVERFLOW | FE_UNDERFLOW) is non-zero, an exception has been raised. An application should either examine the return value or check the floating point exception flags to detect exceptions.

# ATTRIBUTES

See attributes(7) for descriptions of the following attributes:

 ATTRIBUTE TYPE ATTRIBUTE VALUE Interface Stability Standard MT-Level MT-Safe