1 /* Copyright (C) 1991, 1992, 1997, 1999, 2003, 2006, 2008 Free
2 Software Foundation, Inc.
4 This program is free software: you can redistribute it and/or modify
5 it under the terms of the GNU General Public License as published by
6 the Free Software Foundation; either version 3 of the License, or
7 (at your option) any later version.
9 This program is distributed in the hope that it will be useful,
10 but WITHOUT ANY WARRANTY; without even the implied warranty of
11 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
12 GNU General Public License for more details.
14 You should have received a copy of the GNU General Public License
15 along with this program. If not, see <http://www.gnu.org/licenses/>. */
28 /* Convert NPTR to a double. If ENDPTR is not NULL, a pointer to the
29 character after the last one used in the number is put in *ENDPTR. */
31 strtod (const char *nptr, char **endptr)
34 bool negative = false;
36 /* The number so far. */
39 bool got_dot; /* Found a decimal point. */
40 bool got_digit; /* Seen any digits. */
42 /* The exponent of the number. */
54 while (isspace ((unsigned char) *s))
59 if (*s == '-' || *s == '+')
68 if ('0' <= *s && *s <= '9')
72 /* Make sure that multiplication by 10 will not overflow. */
73 if (num > DBL_MAX * 0.1)
74 /* The value of the digit doesn't matter, since we have already
75 gotten as many digits as can be represented in a `double'.
76 This doesn't necessarily mean the result will overflow.
77 The exponent may reduce it to within range.
79 We just need to record that there was another
80 digit so that we can multiply by 10 later. */
83 num = (num * 10.0) + (*s - '0');
85 /* Keep track of the number of digits after the decimal point.
86 If we just divided by 10 here, we would lose precision. */
90 else if (!got_dot && *s == '.')
91 /* Record that we have found the decimal point. */
94 /* Any other character terminates the number. */
100 /* Check for infinities and NaNs. */
101 if (tolower ((unsigned char) *s) == 'i'
102 && tolower ((unsigned char) s[1]) == 'n'
103 && tolower ((unsigned char) s[2]) == 'f')
107 if (tolower ((unsigned char) *s) == 'i'
108 && tolower ((unsigned char) s[1]) == 'n'
109 && tolower ((unsigned char) s[2]) == 'i'
110 && tolower ((unsigned char) s[3]) == 't'
111 && tolower ((unsigned char) s[4]) == 'y')
116 else if (tolower ((unsigned char) *s) == 'n'
117 && tolower ((unsigned char) s[1]) == 'a'
118 && tolower ((unsigned char) s[2]) == 'n')
122 /* Since nan(<n-char-sequence>) is implementation-defined,
123 we define it by ignoring <n-char-sequence>. A nicer
124 implementation would populate the bits of the NaN
125 according to interpreting n-char-sequence as a
126 hexadecimal number, but the result is still a NaN. */
129 const char *p = s + 1;
130 while (isalnum ((unsigned char) *p))
141 if (tolower ((unsigned char) *s) == 'e')
143 /* Get the exponent specified after the `e' or `E'. */
150 exp = strtol (s, &end, 10);
151 if (errno == ERANGE && num)
153 /* The exponent overflowed a `long int'. It is probably a safe
154 assumption that an exponent that cannot be represented by
155 a `long int' exceeds the limits of a `double'. */
164 /* There was no exponent. Reset END to point to
165 the 'e' or 'E', so *ENDPTR will be set there. */
166 end = (char *) s - 1;
175 /* Multiply NUM by 10 to the EXPONENT power,
176 checking for overflow and underflow. */
180 if (num < DBL_MIN * pow (10.0, (double) -exponent))
183 else if (exponent > 0)
185 if (num > DBL_MAX * pow (10.0, (double) -exponent))
189 num *= pow (10.0, (double) exponent);
193 *endptr = (char *) s;
194 return negative ? -num : num;
197 /* Return an overflow error. */
199 *endptr = (char *) s;
201 return negative ? -HUGE_VAL : HUGE_VAL;
204 /* Return an underflow error. */
206 *endptr = (char *) s;
208 return negative ? -0.0 : 0.0;
211 /* There was no number. */
213 *endptr = (char *) nptr;