aboutsummaryrefslogtreecommitdiffstats
path: root/src/string/strcmp.c
blob: bffb2ad99ce5f2874fe7e120f4371fe2572d8377 (plain) (blame)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
/**
 * slibc — Yet another C library
 * Copyright © 2015  Mattias Andrée (maandree@member.fsf.org)
 * 
 * This program is free software: you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 * 
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 * 
 * You should have received a copy of the GNU General Public License
 * along with this program.  If not, see <http://www.gnu.org/licenses/>.
 */
#include <string.h>
#include <strings.h>
#include <stdint.h>
#include <ctype.h>



/**
 * Compare two memory segments alphabetically in a case sensitive manner.
 * 
 * @param   a     A negative value is returned if this is the lesser.
 * @param   b     A positive value is returned if this is the lesser.
 * @param   size  The size of the segments.
 * @return        Zero is returned if `a` and `b` are equal, otherwise,
 *                see the specifications for `a` and `b`.
 */
int memcmp(const void* a, const void* b, size_t size)
{
  const signed char* s1 = a;
  const signed char* s2 = b;
  while (size--)
    if (*s1 == *s2)
      s1++, s2++;
    else
      return (int)(*s1 - *s2);
  return 0;
}


/**
 * Compare two memory segments alphabetically in a case insensitive manner.
 * 
 * This is a slibc extension added because it was useful
 * in implementing slibc itself.
 * 
 * @param   a     A negative value is returned if this is the lesser.
 * @param   b     A positive value is returned if this is the lesser.
 * @param   size  The size of the segments.
 * @return        Zero is returned if `a` and `b` are equal, otherwise,
 *                see the specifications for `a` and `b`.
 */
int memcasecmp(const void* a, const void* b, size_t size)
{
  const signed char* s1 = a;
  const signed char* s2 = b;
  int c1, c2;
  for (; size--; s1++, s2++)
    if (*s1 != *s2)
      {
	c1 = isalpha(*s1) ? tolower(*s1) : (int)*s1;
	c2 = isalpha(*s2) ? tolower(*s2) : (int)*s2;
	if ((c1 -= c2))
	  return c1;
      }
  return 0;
}


/**
 * Compare two strings alphabetically in a case sensitive manner.
 * 
 * @param   a  A negative value is returned if this is the lesser.
 * @param   b  A positive value is returned if this is the lesser.
 * @return     Zero is returned if `a` and `b` are equal, otherwise,
 *             see the specifications for `a` and `b`.
 */
int strcmp(const char* a, const char* b)
{
  size_t n = strlen(a);
  size_t m = strlen(b);
  return memcmp(a, b, (n < m ? n : m) + 1);
}


/**
 * Compare two strings alphabetically in a case insensitive manner.
 * Be aware, only ASCII characters are case insensitive, non-ASCII
 * characters are case sensitive.
 * 
 * @param   a  A negative value is returned if this is the lesser.
 * @param   b  A positive value is returned if this is the lesser.
 * @return     Zero is returned if `a` and `b` are equal, otherwise,
 *             see the specifications for `a` and `b`.
 */
int strcasecmp(const char* a, const char* b)
{
  return strncasecmp(a, b, SIZE_MAX);
}


/**
 * Compare two strings alphabetically in a case sensitive manner.
 * 
 * @param   a       A negative value is returned if this is the lesser.
 * @param   b       A positive value is returned if this is the lesser.
 * @param   length  The maximum number of characters to compare.
 * @return          Zero is returned if `a` and `b` are equal, otherwise,
 *                  see the specifications for `a` and `b`.
 */
int strncmp(const char* a, const char* b, size_t length)
{
  size_t n = strnlen(a, length);
  size_t m = strnlen(b, length);
  int r = memcmp(a, b, (n < m ? n : m));
  return r ? r : n == m ? 0 : n < m ? -1 : +1;
}


/**
 * Compare two strings alphabetically in a case insensitive manner.
 * Be aware, only ASCII characters are case insensitive, non-ASCII
 * characters are case sensitive.
 * 
 * @param   a       A negative value is returned if this is the lesser.
 * @param   b       A positive value is returned if this is the lesser.
 * @param   length  The maximum number of characters to compare.
 * @return          Zero is returned if `a` and `b` are equal, otherwise,
 *                  see the specifications for `a` and `b`.
 */
int strncasecmp(const char* a, const char* b, size_t length)
{
  int c1, c2;
  for (; length--; a++, b++)
    if (*a != *b)
      {
	c1 = isalpha(*a) ? tolower(*a) : (int)*a;
	c2 = isalpha(*b) ? tolower(*b) : (int)*b;
	if ((c1 -= c2))
	  return c1;
      }
    else if (!*a && !*b)  return 0;
    else if (!*a)         return -1;
    else if (!*b)         return +1;
  return 0;
}