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 #include <stdlib.h>
30
31 char *
__utoa(unsigned value,char * str,int base)32 __utoa (unsigned value,
33 char *str,
34 int base)
35 {
36 const char digits[] = "0123456789abcdefghijklmnopqrstuvwxyz";
37 int i, j;
38 unsigned remainder;
39 char c;
40
41 /* Check base is supported. */
42 if ((base < 2) || (base > 36))
43 {
44 str[0] = '\0';
45 return NULL;
46 }
47
48 /* Convert to string. Digits are in reverse order. */
49 i = 0;
50 do
51 {
52 remainder = value % base;
53 str[i++] = digits[remainder];
54 value = value / base;
55 } while (value != 0);
56 str[i] = '\0';
57
58 /* Reverse string. */
59 for (j = 0, i--; j < i; j++, i--)
60 {
61 c = str[j];
62 str[j] = str[i];
63 str[i] = c;
64 }
65
66 return str;
67 }
68
69 char *
utoa(unsigned value,char * str,int base)70 utoa (unsigned value,
71 char *str,
72 int base)
73 {
74 return __utoa (value, str, base);
75 }
76
