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
|
/* strsearch.c
*
* Copyright (c) Chris Putnam 1995-2021
*
* Source code released under the GPL version 2
*
* strsearch() locates a case-independent substring
* e.g. a case-independent version of strstr()
*
* returns pointer to first occurrence of substring needle in
* the string haystack when found, NULL if not found
*
* '\0' characters terminating strings are not compared
*
* strsearch returns haystack when needle is empty as per strstr()
* conventions
*
*/
#include <stdio.h>
#include <ctype.h>
#include "strsearch.h"
char *strsearch (const char *haystack, const char *needle)
{
char *returnptr=NULL;
unsigned long pos=0;
if ( !(*needle) ) returnptr = (char *) haystack;
while (*(haystack+pos) && returnptr==NULL) {
if ( toupper((unsigned char)*(haystack+pos)) == toupper((unsigned char)*(needle+pos)) )
pos++;
else {
pos = 0;
haystack++;
}
if ( ! (*(needle+pos)) ) returnptr = (char *) haystack;
}
return returnptr;
}
|
