strtod.c revision 89857 
1/* Implementation of strtod for systems with atof.
2   Copyright (C) 1991, 1995 Free Software Foundation, Inc.
3
4This file is part of the libiberty library.  This library is free
5software; you can redistribute it and/or modify it under the
6terms of the GNU General Public License as published by the
7Free Software Foundation; either version 2, or (at your option)
8any later version.
9
10This library is distributed in the hope that it will be useful,
11but WITHOUT ANY WARRANTY; without even the implied warranty of
12MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
13GNU General Public License for more details.
14
15You should have received a copy of the GNU General Public License
16along with GNU CC; see the file COPYING.  If not, write to
17the Free Software Foundation, 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
18
19As a special exception, if you link this library with files
20compiled with a GNU compiler to produce an executable, this does not cause
21the resulting executable to be covered by the GNU General Public License.
22This exception does not however invalidate any other reasons why
23the 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
29This 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
31character after the last character used in the conversion is stored in
32the location referenced by @var{endptr}.  If no conversion is
33performed, zero is returned and the value of @var{string} is stored in
34the location referenced by @var{endptr}.
35
36@end deftypefn
37
38*/
39
40#include "ansidecl.h"
41#include "safe-ctype.h"
42
43extern 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
49double
50strtod (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}
139