TRUNC(3) Library Functions Manual TRUNC(3)

trunc, truncf, truncl
nearest integral value with magnitude less than or equal to |x|

Math Library (libm, -lm)

#include <math.h>

double
trunc(double x);

float
truncf(float x);

long double
truncl(long double x);

The trunc(), truncf(), and truncl() functions return the nearest integral value with magnitude less than or equal to |x|. They are equivalent to rint(), rintf(), and rintl() respectively, in the FP_RZ rounding mode.

ceil(3), floor(3), fpsetround(3), math(3), nextafter(3), rint(3), round(3)

The trunc(), truncf(), and truncl() functions conform to ISO/IEC 9899:1999 (“ISO C99”).
November 13, 2013 NetBSD 9.2