stdlib/strtod.3

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  36 .\"     @(#)strtod.3    8.1 (Berkeley) 6/4/93
  37 .\" $FreeBSD: src/lib/libc/stdlib/strtod.3,v 1.13 2001/09/07 14:46:36 asmodai Exp $
  38 .\"
  39 .Dd June 4, 1993
  40 .Dt STRTOD 3
  41 .Os
  42 .Sh NAME
  43 .Nm strtod
  44 .Nd convert
  45 .Tn ASCII
  46 string to double
  47 .Sh LIBRARY
  48 .Lb libc
  49 .Sh SYNOPSIS
  50 .In stdlib.h
  51 .Ft double
  52 .Fn strtod "const char *nptr" "char **endptr"
  53 .Sh DESCRIPTION
  54 The
  55 .Fn strtod
  56 function converts the initial portion of the string
  57 pointed to by
  58 .Fa nptr
  59 to
  60 .Em double
  61 representation.
  62 .Pp
  63 The expected form of the string is an optional plus (``+'') or minus
  64 sign (``\-'') followed by a sequence of digits optionally containing
  65 a decimal-point character, optionally followed by an exponent.
  66 An exponent consists of an ``E'' or ``e'', followed by an optional plus
  67 or minus sign, followed by a sequence of digits.
  68 .Pp
  69 Leading white-space characters in the string (as defined by the
  70 .Xr isspace 3
  71 function) are skipped.
  72 The decimal point
  73 character is defined in the program's locale (category
  74 .Dv LC_NUMERIC ) .
  75 .Sh RETURN VALUES
  76 The
  77 .Fn strtod
  78 function returns the converted value, if any.
  79 .Pp
  80 If
  81 .Fa endptr
  82 is not
  83 .Dv NULL ,
  84 a pointer to the character after the last character used
  85 in the conversion is stored in the location referenced by
  86 .Fa endptr .
  87 .Pp
  88 If no conversion is performed, zero is returned and the value of
  89 .Fa nptr
  90 is stored in the location referenced by
  91 .Fa endptr .
  92 .Pp
  93 If the correct value would cause overflow, plus or minus
  94 .Dv HUGE_VAL
  95 is returned (according to the sign of the value), and
  96 .Er ERANGE
  97 is stored in
  98 .Va errno .
  99 If the correct value would cause underflow, zero is
 100 returned and
 101 .Er ERANGE
 102 is stored in
 103 .Va errno .
 104 .Sh ERRORS
 105 .Bl -tag -width Er
 106 .It Bq Er ERANGE
 107 Overflow or underflow occurred.
 108 .El
 109 .Sh SEE ALSO
 110 .Xr atof 3 ,
 111 .Xr atoi 3 ,
 112 .Xr atol 3 ,
 113 .Xr strtol 3 ,
 114 .Xr strtoul 3
 115 .Sh STANDARDS
 116 The
 117 .Fn strtod
 118 function
 119 conforms to
 120 .St -isoC .
 121 .Sh AUTHORS
 122 The author of this software is
 123 .An David M. Gay .
 124 .Pp
 125 Copyright (c) 1991 by AT&T.
 126 .Pp
 127 Permission to use, copy, modify, and distribute this software for any
 128 purpose without fee is hereby granted, provided that this entire notice
 129 is included in all copies of any software which is or includes a copy
 130 or modification of this software and in all copies of the supporting
 131 documentation for such software.
 132 .Pp
 133 THIS SOFTWARE IS BEING PROVIDED "AS IS", WITHOUT ANY EXPRESS OR IMPLIED
 134 WARRANTY.  IN PARTICULAR, NEITHER THE AUTHOR NOR AT&T MAKES ANY
 135 REPRESENTATION OR WARRANTY OF ANY KIND CONCERNING THE MERCHANTABILITY
 136 OF THIS SOFTWARE OR ITS FITNESS FOR ANY PARTICULAR PURPOSE.
 137 .Pp
 138 Contact your vendor for a free copy of the source code to
 139 .Fn strtod
 140 and accompanying functions.