libiberty/strtod.c

   1 /* Implementation of strtod for systems with atof.
   2    Copyright (C) 1991, 1995 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, 59 Temple Place - Suite 330, Boston, MA 02111-1307, 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}, char **@var{endptr})
  28
  29 This ISO C function converts the initial portion of @var{string} to a
  30 @code{double}.  If @var{endptr} is not @code{NULL}, a pointer to the
  31 character after the last character used in the conversion is stored in
  32 the location referenced by @var{endptr}.  If no conversion is
  33 performed, zero is returned and the value of @var{string} is stored in
  34 the location referenced by @var{endptr}.
  35
  36 @end deftypefn
  37
  38 */
  39
  40 #include "ansidecl.h"
  41 #include "safe-ctype.h"
  42
  43 extern double atof ();
  44
  45 /* Disclaimer: this is currently just used by CHILL in GDB and therefore
  46    has not been tested well.  It may have been tested for nothing except
  47    that it compiles.  */
  48
  49 double
  50 strtod (str, ptr)
  51      char *str;
  52      char **ptr;
  53 {
  54   char *p;
  55
  56   if (ptr == (char **)0)
  57     return atof (str);
  58
  59   p = str;
  60
  61   while (ISSPACE (*p))
  62     ++p;
  63
  64   if (*p == '+' || *p == '-')
  65     ++p;
  66
  67   /* INF or INFINITY.  */
  68   if ((p[0] == 'i' || p[0] == 'I')
  69       && (p[1] == 'n' || p[1] == 'N')
  70       && (p[2] == 'f' || p[2] == 'F'))
  71     {
  72       if ((p[3] == 'i' || p[3] == 'I')
  73           && (p[4] == 'n' || p[4] == 'N')
  74           && (p[5] == 'i' || p[5] == 'I')
  75           && (p[6] == 't' || p[6] == 'T')
  76           && (p[7] == 'y' || p[7] == 'Y'))
  77         {
  78           *ptr = p + 7;
  79           return atof (str);
  80         }
  81       else
  82         {
  83           *ptr = p + 3;
  84           return atof (str);
  85         }
  86     }
  87
  88   /* NAN or NAN(foo).  */
  89   if ((p[0] == 'n' || p[0] == 'N')
  90       && (p[1] == 'a' || p[1] == 'A')
  91       && (p[2] == 'n' || p[2] == 'N'))
  92     {
  93       p += 3;
  94       if (*p == '(')
  95         {
  96           ++p;
  97           while (*p != '\0' && *p != ')')
  98             ++p;
  99           if (*p == ')')
 100             ++p;
 101         }
 102       *ptr = p;
 103       return atof (str);
 104     }
 105
 106   /* digits, with 0 or 1 periods in it.  */
 107   if (ISDIGIT (*p) || *p == '.')
 108     {
 109       int got_dot = 0;
 110       while (ISDIGIT (*p) || (!got_dot && *p == '.'))
 111         {
 112           if (*p == '.')
 113             got_dot = 1;
 114           ++p;
 115         }
 116
 117       /* Exponent.  */
 118       if (*p == 'e' || *p == 'E')
 119         {
 120           int i;
 121           i = 1;
 122           if (p[i] == '+' || p[i] == '-')
 123             ++i;
 124           if (ISDIGIT (p[i]))
 125             {
 126               while (ISDIGIT (p[i]))
 127                 ++i;
 128               *ptr = p + i;
 129               return atof (str);
 130             }
 131         }
 132       *ptr = p;
 133       return atof (str);
 134     }
 135   /* Didn't find any digits.  Doesn't look like a number.  */
 136   *ptr = str;
 137   return 0.0;
 138 }