trunc, truncf, truncl — round to truncated integer value
#include <math.h>
double trunc(double x);
float truncf(float x);
long double truncl(long double x);
[CX] The functionality described on this reference page is aligned with the ISO C standard. Any conflict between the requirements described here and the ISO C standard is unintentional. This volume of POSIX.1-2024 defers to the ISO C standard.These functions shall round their argument to the integer value, in floating format, nearest to but no larger in magnitude than the argument.
[MX] These functions may raise the inexact floating-point exception for finite non-integer arguments.
Upon successful completion, these functions shall return the truncated integer value.
[MX] The returned value shall be exact, shall be independent of the current rounding direction mode, and shall have the same sign as x.[MX] If x is NaN, a NaN shall be returned.
If x is ±0 or ±Inf, x shall be returned.
No errors are defined.
None.
The integral value returned by these functions need not be expressible as an intmax_t. The return value should be tested before assigning it to an integer type to avoid the undefined results of an integer overflow.
None.
None.
XBD <math.h>
First released in Issue 6. Derived from the ISO/IEC 9899:1999 standard.
POSIX.1-2008, Technical Corrigendum 1, XSH/TC1-2008/0684 [346] is applied.
Austin Group Defect 1302 is applied, aligning these functions with the ISO/IEC 9899:2018 standard.
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