1 /* num2long.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 <stddef.h>
34
35 /* Convert a number NUM to a long. The function returns only the integer
36 part of the number. For numbers that are too large to represent as
37 a long, this function returns a zero. This can be detected by checking
38 the NUM for zero after having a zero returned. */
39
bc_num2long(bc_num num)40 long bc_num2long(bc_num num)
41 {
42 /* Extract the int value, ignore the fraction. */
43 long val = 0;
44 const char *nptr = num->n_value;
45 for (size_t index = num->n_len; index > 0; index--) {
46 char n = *nptr++;
47
48 if (val > LONG_MAX / BASE) {
49 return 0;
50 }
51 val *= BASE;
52
53 if (val > LONG_MAX - n) {
54 return 0;
55 }
56 val += n;
57 }
58
59 /* Return the value. */
60 if (num->n_sign == PLUS) {
61 return (val);
62 } else {
63 return (-val);
64 }
65 }
66
