1 /* Copyright (c) 2014 Corinna Vinschen <corinna@vinschen.de> */
2 /*
3 FUNCTION
4 <<utoa>>---unsigned integer to string
5
6 INDEX
7 utoa
8
9 SYNOPSIS
10 #include <stdlib.h>
11 char *utoa(unsigned <[value]>, char *<[str]>, int <[base]>);
12 char *__utoa(unsigned <[value]>, char *<[str]>, int <[base]>);
13
14 DESCRIPTION
15 <<utoa>> converts the unsigned integer [<value>] to a null-terminated string
16 using the specified base, which must be between 2 and 36, inclusive.
17 <[str]> should be an array long enough to contain the converted
18 value, which in the worst case is sizeof(int)*8+1 bytes.
19
20 RETURNS
21 A pointer to the string, <[str]>, or NULL if <[base]> is invalid.
22
23 PORTABILITY
24 <<utoa>> is non-ANSI.
25
26 No supporting OS subroutine calls are required.
27 */
28
29 #define _DEFAULT_SOURCE
30 #include <stdlib.h>
31
32 char *
__utoa(unsigned value,char * str,int base)33 __utoa (unsigned value,
34 char *str,
35 int base)
36 {
37 const char digits[] = "0123456789abcdefghijklmnopqrstuvwxyz";
38 int i, j;
39 unsigned remainder;
40 char c;
41
42 /* Check base is supported. */
43 if ((base < 2) || (base > 36))
44 {
45 str[0] = '\0';
46 return NULL;
47 }
48
49 /* Convert to string. Digits are in reverse order. */
50 i = 0;
51 do
52 {
53 remainder = value % base;
54 str[i++] = digits[remainder];
55 value = value / base;
56 } while (value != 0);
57 str[i] = '\0';
58
59 /* Reverse string. */
60 for (j = 0, i--; j < i; j++, i--)
61 {
62 c = str[j];
63 str[j] = str[i];
64 str[i] = c;
65 }
66
67 return str;
68 }
69
70 char *
utoa(unsigned value,char * str,int base)71 utoa (unsigned value,
72 char *str,
73 int base)
74 {
75 return __utoa (value, str, base);
76 }
77
