1 /* str2num.c: bcmath library file. */
2 /*
3 Copyright (C) 1991, 1992, 1993, 1994, 1997 Free Software Foundation, Inc.
4 Copyright (C) 2000 Philip A. Nelson
5
6 This library is free software; you can redistribute it and/or
7 modify it under the terms of the GNU Lesser General Public
8 License as published by the Free Software Foundation; either
9 version 2 of the License, or (at your option) any later version.
10
11 This library is distributed in the hope that it will be useful,
12 but WITHOUT ANY WARRANTY; without even the implied warranty of
13 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
14 Lesser General Public License for more details. (LICENSE)
15
16 You should have received a copy of the GNU Lesser General Public
17 License along with this library; if not, write to:
18
19 The Free Software Foundation, Inc.
20 59 Temple Place, Suite 330
21 Boston, MA 02111-1307 USA.
22
23 You may contact the author by:
24 e-mail: philnelson@acm.org
25 us-mail: Philip A. Nelson
26 Computer Science Department, 9062
27 Western Washington University
28 Bellingham, WA 98226-9062
29
30 *************************************************************************/
31
32 #include "bcmath.h"
33 #include <stdbool.h>
34 #include <stddef.h>
35
36 /* Convert strings to bc numbers. Base 10 only.*/
37
bc_str2num(bc_num * num,char * str,size_t scale)38 bool bc_str2num(bc_num *num, char *str, size_t scale)
39 {
40 size_t digits = 0;
41 size_t strscale = 0;
42 char *ptr, *nptr;
43 size_t trailing_zeros = 0;
44 bool zero_int = false;
45
46 /* Prepare num. */
47 bc_free_num (num);
48
49 /* Check for valid number and count digits. */
50 ptr = str;
51
52 if ((*ptr == '+') || (*ptr == '-')) {
53 /* Skip Sign */
54 ptr++;
55 }
56 /* Skip leading zeros. */
57 while (*ptr == '0') {
58 ptr++;
59 }
60 /* digits before the decimal point */
61 while (*ptr >= '0' && *ptr <= '9') {
62 ptr++;
63 digits++;
64 }
65 /* decimal point */
66 if (*ptr == '.') {
67 ptr++;
68 }
69 /* digits after the decimal point */
70 while (*ptr >= '0' && *ptr <= '9') {
71 if (*ptr == '0') {
72 trailing_zeros++;
73 } else {
74 trailing_zeros = 0;
75 }
76 ptr++;
77 strscale++;
78 }
79
80 if (trailing_zeros > 0) {
81 /* Trailing zeros should not take part in the computation of the overall scale, as it is pointless. */
82 strscale = strscale - trailing_zeros;
83 }
84 if ((*ptr != '\0') || (digits + strscale == 0)) {
85 *num = bc_copy_num(BCG(_zero_));
86 return *ptr == '\0';
87 }
88
89 /* Adjust numbers and allocate storage and initialize fields. */
90 strscale = MIN(strscale, scale);
91 if (digits == 0) {
92 zero_int = true;
93 digits = 1;
94 }
95 *num = bc_new_num (digits, strscale);
96
97 /* Build the whole number. */
98 ptr = str;
99 if (*ptr == '-') {
100 (*num)->n_sign = MINUS;
101 ptr++;
102 } else {
103 (*num)->n_sign = PLUS;
104 if (*ptr == '+') ptr++;
105 }
106 /* Skip leading zeros. */
107 while (*ptr == '0') {
108 ptr++;
109 }
110 nptr = (*num)->n_value;
111 if (zero_int) {
112 *nptr++ = 0;
113 digits = 0;
114 }
115 for (; digits > 0; digits--) {
116 *nptr++ = CH_VAL(*ptr++);
117 }
118
119 /* Build the fractional part. */
120 if (strscale > 0) {
121 /* skip the decimal point! */
122 ptr++;
123 for (; strscale > 0; strscale--) {
124 *nptr++ = CH_VAL(*ptr++);
125 }
126 }
127
128 if (bc_is_zero(*num)) {
129 (*num)->n_sign = PLUS;
130 }
131
132 return true;
133 }
134
