Mr John FO Evans wrote:
>
I cam across an interesting limitation to the use of strtok.
I have two strings on which I want strtok to operate.
However since strtok has only one memory of the residual string I
must complete one set of operations before starting on the second.
This is inconvenient in the context of my program!
So far the only solution I can see is to write a replacement for
strtok to use on one of the strings. Can anyone offer an
alternative?
Try this:
/* ------- file toksplit.c ----------*/
#include "toksplit.h "
/* copy over the next token from an input string, after
skipping leading blanks (or other whitespace?). The
token is terminated by the first appearance of tokchar,
or by the end of the source string.
The caller must supply sufficient space in token to
receive any token, Otherwise tokens will be truncated.
Returns: a pointer past the terminating tokchar.
This will happily return an infinity of empty tokens if
called with src pointing to the end of a string. Tokens
will never include a copy of tokchar.
A better name would be "strtkn", except that is reserved
for the system namespace. Change to that at your risk.
released to Public Domain, by C.B. Falconer.
Published 2006-02-20. Attribution appreciated.
Revised 2006-06-13
*/
const char *toksplit(const char *src, /* Source of tokens */
char tokchar, /* token delimiting char */
char *token, /* receiver of parsed token */
size_t lgh) /* length token can receive */
/* not including final '\0' */
{
if (src) {
while (' ' == *src) src++;
while (*src && (tokchar != *src)) {
if (lgh) {
*token++ = *src;
--lgh;
}
src++;
}
if (*src && (tokchar == *src)) src++;
}
*token = '\0';
return src;
} /* toksplit */
#ifdef TESTING
#include <stdio.h>
#define ABRsize 6 /* length of acceptable token abbreviations */
/* ---------------- */
static void showtoken(int i, char *tok)
{
putchar(i + '1'); putchar(':');
puts(tok);
} /* showtoken */
/* ---------------- */
int main(void)
{
char teststring[] = "This is a test, ,, abbrev, more";
const char *t, *s = teststring;
int i;
char token[ABRsize + 1];
puts(teststring );
t = s;
for (i = 0; i < 4; i++) {
t = toksplit(t, ',', token, ABRsize);
showtoken(i, token);
}
puts("\nHow to detect 'no more tokens' while truncating");
t = s; i = 0;
while (*t) {
t = toksplit(t, ',', token, 3);
showtoken(i, token);
i++;
}
puts("\nUsing blanks as token delimiters");
t = s; i = 0;
while (*t) {
t = toksplit(t, ' ', token, ABRsize);
showtoken(i, token);
i++;
}
return 0;
} /* main */
#endif
/* ------- end file toksplit.c ----------*/
/* ------- file toksplit.h ----------*/
#ifndef H_toksplit_h
# define H_toksplit_h
# ifdef __cplusplus
extern "C" {
# endif
#include <stddef.h>
/* copy over the next token from an input string, after
skipping leading blanks (or other whitespace?). The
token is terminated by the first appearance of tokchar,
or by the end of the source string.
The caller must supply sufficient space in token to
receive any token, Otherwise tokens will be truncated.
Returns: a pointer past the terminating tokchar.
This will happily return an infinity of empty tokens if
called with src pointing to the end of a string. Tokens
will never include a copy of tokchar.
released to Public Domain, by C.B. Falconer.
Published 2006-02-20. Attribution appreciated.
*/
const char *toksplit(const char *src, /* Source of tokens */
char tokchar, /* token delimiting char */
char *token, /* receiver of parsed token */
size_t lgh); /* length token can receive */
/* not including final '\0' */
# ifdef __cplusplus
}
# endif
#endif
/* ------- end file toksplit.h ----------*/
--
<http://www.cs.auckland .ac.nz/~pgut001/pubs/vista_cost.txt>
<http://www.securityfoc us.com/columnists/423>
"A man who is right every time is not likely to do very much."
-- Francis Crick, co-discover of DNA
"There is nothing more amazing than stupidity in action."
-- Thomas Matthews
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