man3/dysize.3

   1 .\"  Copyright 2001 Walter Harms (walter.harms@informatik.uni-oldenburg.de)
   2 .\"
   3 .\" SPDX-License-Identifier: Linux-man-pages-copyleft
   4 .\"
   5 .\" aeb: some corrections
   6 .TH DYSIZE 3 2021-03-22 "Linux man-pages (unreleased)"
   7 .SH NAME
   8 dysize \- get number of days for a given year
   9 .SH LIBRARY
  10 Standard C library
  11 .RI ( libc ", " \-lc )
  12 .SH SYNOPSIS
  13 .nf
  14 .B "#include <time.h>"
  15 .PP
  16 .BI "int dysize(int " year );
  17 .fi
  18 .PP
  19 .RS -4
  20 Feature Test Macro Requirements for glibc (see
  21 .BR feature_test_macros (7)):
  22 .RE
  23 .PP
  24 .BR dysize ():
  25 .nf
  26     Since glibc 2.19:
  27         _DEFAULT_SOURCE
  28     Glibc 2.19 and earlier:
  29         _BSD_SOURCE || _SVID_SOURCE
  30 .fi
  31 .SH DESCRIPTION
  32 The function returns 365 for a normal year and 366 for a leap year.
  33 The calculation for leap year is based on:
  34 .PP
  35 .in +4n
  36 .EX
  37 (year) %4 == 0 && ((year) %100 != 0 || (year) %400 == 0)
  38 .EE
  39 .in
  40 .PP
  41 The formula is defined in the macro
  42 .I __isleap(year)
  43 also found in
  44 .IR <time.h> .
  45 .SH ATTRIBUTES
  46 For an explanation of the terms used in this section, see
  47 .BR attributes (7).
  48 .ad l
  49 .nh
  50 .TS
  51 allbox;
  52 lbx lb lb
  53 l l l.
  54 Interface       Attribute       Value
  55 T{
  56 .BR dysize ()
  57 T}      Thread safety   MT-Safe
  58 .TE
  59 .hy
  60 .ad
  61 .sp 1
  62 .SH STANDARDS
  63 This function occurs in SunOS 4.x.
  64 .SH NOTES
  65 This is a compatibility function only.
  66 Don't use it in new programs.
  67 .\" The SCO version of this function had a year-2000 problem.
  68 .SH SEE ALSO
  69 .BR strftime (3)