strtok関数 自作

質問

strtok関数の内部の処理がしりたいので、自作された事がある方はぜひソースプログラムを教えてください。

回答No.2

BLK314 · ベストアンサー

1: /*
2: * (c) copyright 1987 by the Vrije Universiteit, Amsterdam, The Netherlands.
3: * See the copyright notice in the ACK home directory, in the file "Copyright".
4: */
5: /* $Header: strspn.c,v 1.1 89/05/11 10:09:09 eck Exp $ */
6:
7: #include <string.h>
8:
9: size_t
10: strspn(const char *string, const char *in)
11: {
12: register const char *s1, *s2;
13:
14: for (s1 = string; *s1; s1++) {
15: for (s2 = in; *s2 && *s2 != *s1; s2++)
16: /* EMPTY */ ;
17: if (*s2 == '\0')
18: break;
19: }
20: return s1 - string;
21: }

回答No.3

BLK314

1: /*
2: * (c) copyright 1987 by the Vrije Universiteit, Amsterdam, The Netherlands.
3: * See the copyright notice in the ACK home directory, in the file "Copyright".
4: */
5: /* $Header: strpbrk.c,v 1.2 89/12/18 16:02:21 eck Exp $ */
6:
7: #include <string.h>
8:
9: char *
10: strpbrk(register const char *string, register const char *brk)
11: {
12: register const char *s1;
13:
14: while (*string) {
15: for (s1 = brk; *s1 && *s1 != *string; s1++)
16: /* EMPTY */ ;
17: if (*s1)
18: return (char *)string;
19: string++;
20: }
21: return (char *)NULL;
22: }

回答No.1

BLK314

/*
* (c) copyright 1987 by the Vrije Universiteit, Amsterdam, The Netherlands.
* See the copyright notice in the ACK home directory, in the file "Copyright".
*/
/* $Header: strtok.c,v 1.2 90/08/28 13:54:38 eck Exp $ */

#include <string.h>

char *
strtok(register char *string, const char *separators)
{
register char *s1, *s2;
static char *savestring;

if (string == NULL) {
string = savestring;
if (string == NULL) return (char *)NULL;
}

s1 = string + strspn(string, separators);
if (*s1 == '\0') {
savestring = NULL;
return (char *)NULL;
}

s2 = strpbrk(s1, separators);
if (s2 != NULL)
*s2++ = '\0';
savestring = s2;
return s1;
}

お礼

ありがとうございました！！