ISLESS(3)                  POSIX Programmer's Manual                 ISLESS(3)



PPRROOLLOOGG
       This manual page is part of the POSIX Programmer's Manual.  The OS
       implementation of this interface may differ (consult the corresponding
       OS manual page for details of OS behavior), or the interface may not be
       implemented on OS.

NNAAMMEE
       isless -- test if x is less than y

SSYYNNOOPPSSIISS
       #include <math.h>

       int isless(real-floating _x, real-floating _y);

DDEESSCCRRIIPPTTIIOONN
       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.1-2017
       defers to the ISO C standard.

       The _i_s_l_e_s_s() macro shall determine whether its first argument is less
       than its second argument. The value of _i_s_l_e_s_s(_x, _y) shall be equal to
       (_x) < (_y); however, unlike (_x) < (_y), _i_s_l_e_s_s(_x, _y) shall not raise the
       invalid floating-point exception when _x and _y are unordered.

RREETTUURRNN VVAALLUUEE
       Upon successful completion, the _i_s_l_e_s_s() macro shall return the value
       of (_x) < (_y).

       If _x or _y is NaN, 0 shall be returned.

EERRRROORRSS
       No errors are defined.

       _T_h_e _f_o_l_l_o_w_i_n_g _s_e_c_t_i_o_n_s _a_r_e _i_n_f_o_r_m_a_t_i_v_e_.

EEXXAAMMPPLLEESS
       None.

AAPPPPLLIICCAATTIIOONN UUSSAAGGEE
       The relational and equality operators support the usual mathematical
       relationships between numeric values. For any ordered pair of numeric
       values, exactly one of the relationships (less, greater, and equal) is
       true. Relational operators may raise the invalid floating-point
       exception when argument values are NaNs. For a NaN and a numeric value,
       or for two NaNs, just the unordered relationship is true. This macro is
       a quiet (non-floating-point exception raising) version of a relational
       operator. It facilitates writing efficient code that accounts for NaNs
       without suffering the invalid floating-point exception. In the SYNOPSIS
       section, rreeaall--ffllooaattiinngg indicates that the argument shall be an
       expression of rreeaall--ffllooaattiinngg type.

RRAATTIIOONNAALLEE
       None.

FFUUTTUURREE DDIIRREECCTTIIOONNSS
       None.

SSEEEE AALLSSOO
       _i_s_g_r_e_a_t_e_r(), _i_s_g_r_e_a_t_e_r_e_q_u_a_l(), _i_s_l_e_s_s_e_q_u_a_l(), _i_s_l_e_s_s_g_r_e_a_t_e_r(),
       _i_s_u_n_o_r_d_e_r_e_d()

       The Base Definitions volume of POSIX.1-2017, <<mmaatthh..hh>>

CCOOPPYYRRIIGGHHTT
       Portions of this text are reprinted and reproduced in electronic form
       from IEEE Std 1003.1-2017, Standard for Information Technology --
       Portable Operating System Interface (POSIX), The Open Group Base
       Specifications Issue 7, 2018 Edition, Copyright (C) 2018 by the
       Institute of Electrical and Electronics Engineers, Inc and The Open
       Group.  In the event of any discrepancy between this version and the
       original IEEE and The Open Group Standard, the original IEEE and The
       Open Group Standard is the referee document. The original Standard can
       be obtained online at http://www.opengroup.org/unix/online.html .

       Any typographical or formatting errors that appear in this page are
       most likely to have been introduced during the conversion of the source
       files to man page format. To report such errors, see
       https://www.kernel.org/doc/man-pages/reporting_bugs.html .



IEEE/The Open Group                  2017                            ISLESS(3)
