stdtime/FreeBSD/strptime.3

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  28 .Dd October 2, 2014
  29 .Dt STRPTIME 3
  30 .Os
  31 .Sh NAME
  32 .Nm strptime ,
  33 .Nm strptime_l
  34 .Nd parse date and time string
  35 .Sh LIBRARY
  36 .Lb libc
  37 .Sh SYNOPSIS
  38 .In time.h
  39 .Ft char *
  40 .Fo strptime
  41 .Fa "const char * restrict buf"
  42 .Fa "const char * restrict format"
  43 .Fa "struct tm * restrict timeptr"
  44 .Fc
  45 .In time.h
  46 .In xlocale.h
  47 .Ft char *
  48 .Fn strptime_l "const char * restrict buf" "const char * restrict format" "struct tm * restrict timeptr" "locale_t loc"
  49 .Sh DESCRIPTION
  50 The
  51 .Fn strptime
  52 function parses the string in the buffer
  53 .Fa buf
  54 according to the string pointed to by
  55 .Fa format ,
  56 and fills in the elements of the structure pointed to by
  57 .Fa timeptr .
  58 The resulting values will be relative to the local time zone.
  59 Thus, it can be considered the reverse operation of
  60 .Xr strftime 3 .
  61 The
  62 .Fn strptime_l
  63 function does the same as
  64 .Fn strptime ,
  65 but takes an explicit locale rather than using the current locale.
  66 .Pp
  67 The
  68 .Fa format
  69 string consists of zero or more conversion specifications and
  70 ordinary characters.
  71 All ordinary characters are matched exactly with the buffer, where
  72 white space in the format string will match any amount of white space
  73 in the buffer.
  74 All conversion specifications are identical to those described in
  75 .Xr strftime 3 .
  76 .Pp
  77 Two-digit year values, including formats
  78 .Fa %y
  79 and
  80 .Fa \&%D ,
  81 are now interpreted as beginning at 1969 per POSIX requirements.
  82 Years 69-00 are interpreted in the 20th century (1969-2000), years
  83 01-68 in the 21st century (2001-2068).
  84 The
  85 .Fa \&%U
  86 and
  87 .Fa %W
  88 format specifiers accept any value within the range 00 to 53.
  89 .Pp
  90 If the
  91 .Fa format
  92 string does not contain enough conversion specifications to completely
  93 specify the resulting
  94 .Vt struct tm ,
  95 the unspecified members of
  96 .Va timeptr
  97 are left untouched.
  98 For example, if
  99 .Fa format
 100 is
 101 .Dq Li "%H:%M:%S" ,
 102 only
 103 .Va tm_hour ,
 104 .Va tm_sec
 105 and
 106 .Va tm_min
 107 will be modified.
 108 If time relative to today is desired, initialize the
 109 .Fa timeptr
 110 structure with today's date before passing it to
 111 .Fn strptime .
 112 .Sh RETURN VALUES
 113 Upon successful completion,
 114 .Fn strptime
 115 returns the pointer to the first character in
 116 .Fa buf
 117 that has not been required to satisfy the specified conversions in
 118 .Fa format .
 119 It returns
 120 .Dv NULL
 121 if one of the conversions failed.
 122 .Fn strptime_l
 123 returns the same values as
 124 .Fn strptime .
 125 .Sh LEGACY DESCRIPTION
 126 In legacy mode, the
 127 .Fa %Y
 128 format specifier expects exactly 4 digits (leaving any trailing digits for the
 129 next specifier).
 130 .Sh SEE ALSO
 131 .Xr date 1 ,
 132 .Xr scanf 3 ,
 133 .Xr strftime 3 ,
 134 .Xr xlocale 3
 135 .Sh HISTORY
 136 The
 137 .Fn strptime
 138 function appeared in
 139 .Fx 3.0 .
 140 .Sh AUTHORS
 141 The
 142 .Fn strptime
 143 function has been contributed by Powerdog Industries.
 144 .Pp
 145 This man page was written by
 146 .An J\(:org Wunsch .
 147 .Sh BUGS
 148 Both the
 149 .Fa %e
 150 and
 151 .Fa %l
 152 format specifiers may incorrectly scan one too many digits
 153 if the intended values comprise only a single digit
 154 and that digit is followed immediately by another digit.
 155 Both specifiers accept zero-padded values,
 156 even though they are both defined as taking unpadded values.
 157 .Pp
 158 The
 159 .Fa %p
 160 format specifier has no effect unless it is parsed
 161 .Em after
 162 hour-related specifiers.
 163 Specifying
 164 .Fa %l
 165 without
 166 .Fa %p
 167 will produce undefined results.
 168 Note that 12AM
 169 (ante meridiem)
 170 is taken as midnight
 171 and 12PM
 172 (post meridiem)
 173 is taken as noon.
 174 .Pp
 175 The
 176 .Fa %Z
 177 format specifier only accepts time zone abbreviations of the local time zone,
 178 or the value "GMT".
 179 This limitation is because of ambiguity due to of the over loading of time
 180 zone abbreviations.
 181 One such example is
 182 .Fa EST
 183 which is both Eastern Standard Time and Eastern Australia Summer Time.
 184 .Pp
 185 The
 186 .Fn strptime
 187 function does not correctly handle multibyte characters in the
 188 .Fa format
 189 argument.