Mercurial > gnulib
annotate lib/strtod.c @ 2807:807294ed0f4f
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| author | Jim Meyering <jim@meyering.net> |
|---|---|
| date | Mon, 07 Aug 2000 15:48:18 +0000 |
| parents | 5994c6f939c5 |
| children | ce37d22a271f |
| rev | line source |
|---|---|
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2807
807294ed0f4f
back out Copyright date changes for files with no changes year
Jim Meyering <jim@meyering.net>
parents:
2718
diff
changeset
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1 /* Copyright (C) 1991, 1992, 1997, 1999 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 |
| 728 | 40 #if HAVE_FLOAT_H |
| 41 # include <float.h> | |
| 311 | 42 #else |
| 728 | 43 # define DBL_MAX 1.7976931348623159e+308 |
| 44 # define DBL_MIN 2.2250738585072010e-308 | |
| 311 | 45 #endif |
| 309 | 46 |
| 311 | 47 #if STDC_HEADERS |
| 728 | 48 # include <stdlib.h> |
| 49 # include <string.h> | |
| 311 | 50 #else |
| 728 | 51 # define NULL 0 |
| 52 # ifndef HUGE_VAL | |
| 53 # define HUGE_VAL HUGE | |
| 54 # endif | |
| 311 | 55 #endif |
| 9 | 56 |
| 57 /* Convert NPTR to a double. If ENDPTR is not NULL, a pointer to the | |
| 58 character after the last one used in the number is put in *ENDPTR. */ | |
| 59 double | |
| 1691 | 60 strtod (const char *nptr, char **endptr) |
| 9 | 61 { |
| 311 | 62 register const char *s; |
| 9 | 63 short int sign; |
| 64 | |
| 65 /* The number so far. */ | |
| 66 double num; | |
| 67 | |
| 311 | 68 int got_dot; /* Found a decimal point. */ |
| 69 int got_digit; /* Seen any digits. */ | |
| 9 | 70 |
| 71 /* The exponent of the number. */ | |
| 72 long int exponent; | |
| 73 | |
| 74 if (nptr == NULL) | |
| 75 { | |
| 76 errno = EINVAL; | |
| 77 goto noconv; | |
| 78 } | |
| 79 | |
| 80 s = nptr; | |
| 81 | |
| 82 /* Eat whitespace. */ | |
| 1042 | 83 while (ISSPACE (*s)) |
| 9 | 84 ++s; |
| 85 | |
| 86 /* Get the sign. */ | |
| 87 sign = *s == '-' ? -1 : 1; | |
| 88 if (*s == '-' || *s == '+') | |
| 89 ++s; | |
| 90 | |
| 91 num = 0.0; | |
| 92 got_dot = 0; | |
| 93 got_digit = 0; | |
| 94 exponent = 0; | |
| 95 for (;; ++s) | |
| 96 { | |
| 1042 | 97 if (ISDIGIT (*s)) |
| 9 | 98 { |
| 99 got_digit = 1; | |
| 100 | |
| 101 /* Make sure that multiplication by 10 will not overflow. */ | |
| 102 if (num > DBL_MAX * 0.1) | |
| 103 /* The value of the digit doesn't matter, since we have already | |
| 104 gotten as many digits as can be represented in a `double'. | |
| 105 This doesn't necessarily mean the result will overflow. | |
| 106 The exponent may reduce it to within range. | |
| 107 | |
| 108 We just need to record that there was another | |
| 109 digit so that we can multiply by 10 later. */ | |
| 110 ++exponent; | |
| 111 else | |
| 112 num = (num * 10.0) + (*s - '0'); | |
| 113 | |
| 114 /* Keep track of the number of digits after the decimal point. | |
| 115 If we just divided by 10 here, we would lose precision. */ | |
| 116 if (got_dot) | |
| 117 --exponent; | |
| 118 } | |
| 311 | 119 else if (!got_dot && *s == '.') |
| 9 | 120 /* Record that we have found the decimal point. */ |
| 121 got_dot = 1; | |
| 122 else | |
| 123 /* Any other character terminates the number. */ | |
| 124 break; | |
| 125 } | |
| 126 | |
| 127 if (!got_digit) | |
| 128 goto noconv; | |
| 129 | |
| 1042 | 130 if (TOLOWER (*s) == 'e') |
| 9 | 131 { |
| 132 /* Get the exponent specified after the `e' or `E'. */ | |
| 133 int save = errno; | |
| 134 char *end; | |
| 135 long int exp; | |
| 136 | |
| 137 errno = 0; | |
| 138 ++s; | |
| 311 | 139 exp = strtol (s, &end, 10); |
| 9 | 140 if (errno == ERANGE) |
| 141 { | |
| 142 /* The exponent overflowed a `long int'. It is probably a safe | |
| 143 assumption that an exponent that cannot be represented by | |
| 144 a `long int' exceeds the limits of a `double'. */ | |
| 145 if (endptr != NULL) | |
| 146 *endptr = end; | |
| 147 if (exp < 0) | |
| 148 goto underflow; | |
| 149 else | |
| 150 goto overflow; | |
| 151 } | |
| 152 else if (end == s) | |
| 153 /* There was no exponent. Reset END to point to | |
| 154 the 'e' or 'E', so *ENDPTR will be set there. */ | |
| 155 end = (char *) s - 1; | |
| 156 errno = save; | |
| 157 s = end; | |
| 158 exponent += exp; | |
| 159 } | |
| 160 | |
| 161 if (endptr != NULL) | |
| 162 *endptr = (char *) s; | |
| 163 | |
| 164 if (num == 0.0) | |
| 165 return 0.0; | |
| 166 | |
| 167 /* Multiply NUM by 10 to the EXPONENT power, | |
| 168 checking for overflow and underflow. */ | |
| 169 | |
| 170 if (exponent < 0) | |
| 171 { | |
| 311 | 172 if (num < DBL_MIN * pow (10.0, (double) -exponent)) |
| 9 | 173 goto underflow; |
| 174 } | |
| 175 else if (exponent > 0) | |
| 176 { | |
| 311 | 177 if (num > DBL_MAX * pow (10.0, (double) -exponent)) |
| 9 | 178 goto overflow; |
| 179 } | |
| 180 | |
| 311 | 181 num *= pow (10.0, (double) exponent); |
| 9 | 182 |
| 183 return num * sign; | |
| 184 | |
| 311 | 185 overflow: |
| 9 | 186 /* Return an overflow error. */ |
| 187 errno = ERANGE; | |
| 188 return HUGE_VAL * sign; | |
| 189 | |
| 311 | 190 underflow: |
| 9 | 191 /* Return an underflow error. */ |
| 192 if (endptr != NULL) | |
| 193 *endptr = (char *) nptr; | |
| 194 errno = ERANGE; | |
| 195 return 0.0; | |
| 196 | |
| 311 | 197 noconv: |
| 9 | 198 /* There was no number. */ |
| 199 if (endptr != NULL) | |
| 200 *endptr = (char *) nptr; | |
| 201 return 0.0; | |
| 202 } |