stdlib/FreeBSD/atof.3

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  32 .\"     @(#)atof.3      8.1 (Berkeley) 6/4/93
  33 .\" $FreeBSD: src/lib/libc/stdlib/atof.3,v 1.17 2007/01/09 00:28:09 imp Exp $
  34 .\"
  35 .Dd June 4, 1993
  36 .Dt ATOF 3
  37 .Os
  38 .Sh NAME
  39 .Nm atof ,
  40 .Nm atof_l
  41 .Nd convert
  42 .Tn ASCII
  43 string to double
  44 .Sh LIBRARY
  45 .Lb libc
  46 .Sh SYNOPSIS
  47 .In stdlib.h
  48 .Ft double
  49 .Fn atof "const char *str"
  50 .In xlocale.h
  51 .Ft double
  52 .Fn atof_l "const char *str" "locale_t loc"
  53 .Sh DESCRIPTION
  54 The
  55 .Fn atof
  56 function converts the initial portion of the string pointed to by
  57 .Fa str
  58 to
  59 .Vt double
  60 representation.
  61 .Pp
  62 It is equivalent to:
  63 .Bd -literal -offset indent
  64 strtod(str, (char **)NULL);
  65 .Ed
  66 .Pp
  67 The decimal point
  68 character is defined in the program's locale (category
  69 .Dv LC_NUMERIC ) .
  70 .Pp
  71 While the
  72 .Fn atof
  73 function uses the current locale, the
  74 .Fn atof_l
  75 function may be passed a locale directly. See
  76 .Xr xlocale 3
  77 for more information.
  78 .Sh IMPLEMENTATION NOTES
  79 The
  80 .Fn atof
  81 and
  82 .Fn atof_l
  83 functions are thread-safe and async-cancel-safe.
  84 .Pp
  85 The
  86 .Fn strtod
  87 and
  88 .Fn strtod_l
  89 functions are recommended instead of
  90 .Fn atof
  91 and
  92 .Fn atof_l
  93 functions, especially in new code.
  94 .Sh ERRORS
  95 The function
  96 .Fn atof
  97 need not affect the value of
  98 .Va errno
  99 on an error.
 100 .Sh SEE ALSO
 101 .Xr atoi 3 ,
 102 .Xr atol 3 ,
 103 .Xr strtod 3 ,
 104 .Xr strtol 3 ,
 105 .Xr strtoul 3 ,
 106 .Xr xlocale 3
 107 .Sh STANDARDS
 108 The
 109 .Fn atof
 110 function conforms to
 111 .St -p1003.1-90 ,
 112 .St -isoC ,
 113 and
 114 .St -isoC-99 .