Mercurial > gnulib
annotate lib/strtod.c @ 4691:ce37d22a271f
Remove K&R cruft.
| author | Paul Eggert <eggert@cs.ucla.edu> |
|---|---|
| date | Fri, 12 Sep 2003 18:24:51 +0000 |
| parents | 807294ed0f4f |
| children | a48fb0e98c8c |
| rev | line source |
|---|---|
| 4691 | 1 /* Copyright (C) 1991, 1992, 1997, 1999, 2003 Free Software Foundation, Inc. |
| 9 | 2 |
| 311 | 3 This program is free software; you can redistribute it and/or modify |
| 4 it under the terms of the GNU General Public License as published by | |
| 5 the Free Software Foundation; either version 2, or (at your option) | |
| 6 any later version. | |
| 9 | 7 |
| 311 | 8 This program is distributed in the hope that it will be useful, |
| 9 but WITHOUT ANY WARRANTY; without even the implied warranty of | |
| 10 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the | |
| 11 GNU General Public License for more details. | |
| 12 | |
| 13 You should have received a copy of the GNU General Public License | |
|
649
89f4c1937ac7
update FSF address in copyright and remove any trailing blanks
Jim Meyering <jim@meyering.net>
parents:
373
diff
changeset
|
14 along with this program; if not, write to the Free Software Foundation, |
|
89f4c1937ac7
update FSF address in copyright and remove any trailing blanks
Jim Meyering <jim@meyering.net>
parents:
373
diff
changeset
|
15 Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA. */ |
| 309 | 16 |
| 728 | 17 #if HAVE_CONFIG_H |
| 18 # include <config.h> | |
| 311 | 19 #endif |
| 20 | |
| 21 #include <errno.h> | |
| 373 | 22 #ifndef errno |
| 23 extern int errno; | |
| 24 #endif | |
| 25 | |
| 311 | 26 #include <ctype.h> |
| 1042 | 27 |
| 28 #if defined (STDC_HEADERS) || (!defined (isascii) && !defined (HAVE_ISASCII)) | |
| 29 # define IN_CTYPE_DOMAIN(c) 1 | |
| 30 #else | |
| 31 # define IN_CTYPE_DOMAIN(c) isascii(c) | |
| 32 #endif | |
| 33 | |
| 34 #define ISSPACE(c) (IN_CTYPE_DOMAIN (c) && isspace (c)) | |
| 35 #define ISDIGIT(c) (IN_CTYPE_DOMAIN (c) && isdigit (c)) | |
| 36 #define TOLOWER(c) (IN_CTYPE_DOMAIN (c) ? tolower(c) : (c)) | |
| 37 | |
| 311 | 38 #include <math.h> |
| 9 | 39 |
| 4691 | 40 #include <float.h> |
| 41 #include <stdlib.h> | |
| 42 #include <string.h> | |
| 9 | 43 |
| 44 /* Convert NPTR to a double. If ENDPTR is not NULL, a pointer to the | |
| 45 character after the last one used in the number is put in *ENDPTR. */ | |
| 46 double | |
| 1691 | 47 strtod (const char *nptr, char **endptr) |
| 9 | 48 { |
| 311 | 49 register const char *s; |
| 9 | 50 short int sign; |
| 51 | |
| 52 /* The number so far. */ | |
| 53 double num; | |
| 54 | |
| 311 | 55 int got_dot; /* Found a decimal point. */ |
| 56 int got_digit; /* Seen any digits. */ | |
| 9 | 57 |
| 58 /* The exponent of the number. */ | |
| 59 long int exponent; | |
| 60 | |
| 61 if (nptr == NULL) | |
| 62 { | |
| 63 errno = EINVAL; | |
| 64 goto noconv; | |
| 65 } | |
| 66 | |
| 67 s = nptr; | |
| 68 | |
| 69 /* Eat whitespace. */ | |
| 1042 | 70 while (ISSPACE (*s)) |
| 9 | 71 ++s; |
| 72 | |
| 73 /* Get the sign. */ | |
| 74 sign = *s == '-' ? -1 : 1; | |
| 75 if (*s == '-' || *s == '+') | |
| 76 ++s; | |
| 77 | |
| 78 num = 0.0; | |
| 79 got_dot = 0; | |
| 80 got_digit = 0; | |
| 81 exponent = 0; | |
| 82 for (;; ++s) | |
| 83 { | |
| 1042 | 84 if (ISDIGIT (*s)) |
| 9 | 85 { |
| 86 got_digit = 1; | |
| 87 | |
| 88 /* Make sure that multiplication by 10 will not overflow. */ | |
| 89 if (num > DBL_MAX * 0.1) | |
| 90 /* The value of the digit doesn't matter, since we have already | |
| 91 gotten as many digits as can be represented in a `double'. | |
| 92 This doesn't necessarily mean the result will overflow. | |
| 93 The exponent may reduce it to within range. | |
| 94 | |
| 95 We just need to record that there was another | |
| 96 digit so that we can multiply by 10 later. */ | |
| 97 ++exponent; | |
| 98 else | |
| 99 num = (num * 10.0) + (*s - '0'); | |
| 100 | |
| 101 /* Keep track of the number of digits after the decimal point. | |
| 102 If we just divided by 10 here, we would lose precision. */ | |
| 103 if (got_dot) | |
| 104 --exponent; | |
| 105 } | |
| 311 | 106 else if (!got_dot && *s == '.') |
| 9 | 107 /* Record that we have found the decimal point. */ |
| 108 got_dot = 1; | |
| 109 else | |
| 110 /* Any other character terminates the number. */ | |
| 111 break; | |
| 112 } | |
| 113 | |
| 114 if (!got_digit) | |
| 115 goto noconv; | |
| 116 | |
| 1042 | 117 if (TOLOWER (*s) == 'e') |
| 9 | 118 { |
| 119 /* Get the exponent specified after the `e' or `E'. */ | |
| 120 int save = errno; | |
| 121 char *end; | |
| 122 long int exp; | |
| 123 | |
| 124 errno = 0; | |
| 125 ++s; | |
| 311 | 126 exp = strtol (s, &end, 10); |
| 9 | 127 if (errno == ERANGE) |
| 128 { | |
| 129 /* The exponent overflowed a `long int'. It is probably a safe | |
| 130 assumption that an exponent that cannot be represented by | |
| 131 a `long int' exceeds the limits of a `double'. */ | |
| 132 if (endptr != NULL) | |
| 133 *endptr = end; | |
| 134 if (exp < 0) | |
| 135 goto underflow; | |
| 136 else | |
| 137 goto overflow; | |
| 138 } | |
| 139 else if (end == s) | |
| 140 /* There was no exponent. Reset END to point to | |
| 141 the 'e' or 'E', so *ENDPTR will be set there. */ | |
| 142 end = (char *) s - 1; | |
| 143 errno = save; | |
| 144 s = end; | |
| 145 exponent += exp; | |
| 146 } | |
| 147 | |
| 148 if (endptr != NULL) | |
| 149 *endptr = (char *) s; | |
| 150 | |
| 151 if (num == 0.0) | |
| 152 return 0.0; | |
| 153 | |
| 154 /* Multiply NUM by 10 to the EXPONENT power, | |
| 155 checking for overflow and underflow. */ | |
| 156 | |
| 157 if (exponent < 0) | |
| 158 { | |
| 311 | 159 if (num < DBL_MIN * pow (10.0, (double) -exponent)) |
| 9 | 160 goto underflow; |
| 161 } | |
| 162 else if (exponent > 0) | |
| 163 { | |
| 311 | 164 if (num > DBL_MAX * pow (10.0, (double) -exponent)) |
| 9 | 165 goto overflow; |
| 166 } | |
| 167 | |
| 311 | 168 num *= pow (10.0, (double) exponent); |
| 9 | 169 |
| 170 return num * sign; | |
| 171 | |
| 311 | 172 overflow: |
| 9 | 173 /* Return an overflow error. */ |
| 174 errno = ERANGE; | |
| 175 return HUGE_VAL * sign; | |
| 176 | |
| 311 | 177 underflow: |
| 9 | 178 /* Return an underflow error. */ |
| 179 if (endptr != NULL) | |
| 180 *endptr = (char *) nptr; | |
| 181 errno = ERANGE; | |
| 182 return 0.0; | |
| 183 | |
| 311 | 184 noconv: |
| 9 | 185 /* There was no number. */ |
| 186 if (endptr != NULL) | |
| 187 *endptr = (char *) nptr; | |
| 188 return 0.0; | |
| 189 } |