libiberty/strtod.c

   1 /* Implementation of strtod for systems with atof.
   2    Copyright (C) 1991-2023 Free Software Foundation, Inc.
   3
   4 This file is part of the libiberty library.  This library is free
   5 software; you can redistribute it and/or modify it under the
   6 terms of the GNU General Public License as published by the
   7 Free Software Foundation; either version 2, or (at your option)
   8 any later version.
   9
  10 This library is distributed in the hope that it will be useful,
  11 but WITHOUT ANY WARRANTY; without even the implied warranty of
  12 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  13 GNU General Public License for more details.
  14
  15 You should have received a copy of the GNU General Public License
  16 along with GNU CC; see the file COPYING.  If not, write to
  17 the Free Software Foundation, 51 Franklin Street - Fifth Floor, Boston, MA 02110-1301, USA.
  18
  19 As a special exception, if you link this library with files
  20 compiled with a GNU compiler to produce an executable, this does not cause
  21 the resulting executable to be covered by the GNU General Public License.
  22 This exception does not however invalidate any other reasons why
  23 the executable file might be covered by the GNU General Public License. */
  24
  25 /*
  26
  27 @deftypefn Supplemental double strtod (const char *@var{string}, @
  28   char **@var{endptr})
  29
  30 This ISO C function converts the initial portion of @var{string} to a
  31 @code{double}.  If @var{endptr} is not @code{NULL}, a pointer to the
  32 character after the last character used in the conversion is stored in
  33 the location referenced by @var{endptr}.  If no conversion is
  34 performed, zero is returned and the value of @var{string} is stored in
  35 the location referenced by @var{endptr}.
  36
  37 @end deftypefn
  38
  39 */
  40
  41 #include "ansidecl.h"
  42 #include "safe-ctype.h"
  43
  44 extern double atof (const char *);
  45
  46 /* Disclaimer: this is currently just used by CHILL in GDB and therefore
  47    has not been tested well.  It may have been tested for nothing except
  48    that it compiles.  */
  49
  50 double
  51 strtod (char *str, char **ptr)
  52 {
  53   char *p;
  54
  55   if (ptr == (char **)0)
  56     return atof (str);
  57
  58   p = str;
  59
  60   while (ISSPACE (*p))
  61     ++p;
  62
  63   if (*p == '+' || *p == '-')
  64     ++p;
  65
  66   /* INF or INFINITY.  */
  67   if ((p[0] == 'i' || p[0] == 'I')
  68       && (p[1] == 'n' || p[1] == 'N')
  69       && (p[2] == 'f' || p[2] == 'F'))
  70     {
  71       if ((p[3] == 'i' || p[3] == 'I')
  72           && (p[4] == 'n' || p[4] == 'N')
  73           && (p[5] == 'i' || p[5] == 'I')
  74           && (p[6] == 't' || p[6] == 'T')
  75           && (p[7] == 'y' || p[7] == 'Y'))
  76         {
  77           *ptr = p + 8;
  78           return atof (str);
  79         }
  80       else
  81         {
  82           *ptr = p + 3;
  83           return atof (str);
  84         }
  85     }
  86
  87   /* NAN or NAN(foo).  */
  88   if ((p[0] == 'n' || p[0] == 'N')
  89       && (p[1] == 'a' || p[1] == 'A')
  90       && (p[2] == 'n' || p[2] == 'N'))
  91     {
  92       p += 3;
  93       if (*p == '(')
  94         {
  95           ++p;
  96           while (*p != '\0' && *p != ')')
  97             ++p;
  98           if (*p == ')')
  99             ++p;
 100         }
 101       *ptr = p;
 102       return atof (str);
 103     }
 104
 105   /* digits, with 0 or 1 periods in it.  */
 106   if (ISDIGIT (*p) || *p == '.')
 107     {
 108       int got_dot = 0;
 109       while (ISDIGIT (*p) || (!got_dot && *p == '.'))
 110         {
 111           if (*p == '.')
 112             got_dot = 1;
 113           ++p;
 114         }
 115
 116       /* Exponent.  */
 117       if (*p == 'e' || *p == 'E')
 118         {
 119           int i;
 120           i = 1;
 121           if (p[i] == '+' || p[i] == '-')
 122             ++i;
 123           if (ISDIGIT (p[i]))
 124             {
 125               while (ISDIGIT (p[i]))
 126                 ++i;
 127               *ptr = p + i;
 128               return atof (str);
 129             }
 130         }
 131       *ptr = p;
 132       return atof (str);
 133     }
 134   /* Didn't find any digits.  Doesn't look like a number.  */
 135   *ptr = str;
 136   return 0.0;
 137 }