string function

[dimitris67]

How can I replace an occurence of p(a string) in an other string(s) with
np(new string)..
char* replace _pattern(char *s,char *p,char *np)
PLEASE HELP ME!!!!!

[CBFalconer]

dimitris67 wrote:

How can I replace an occurence of p(a string) in an other string(s)
with np(new string)..
char* replace _pattern(char *s,char *p,char *np)

sed (in the unix, DJGPP, cygwin, mingw worlds) will do it nicely.
If he wants C source code to do it for multiple identifiers in one
pass, see:

<http://cbfalconer.home .att.net/download/id2id-20.zip>

no patterns there, just exact identifiers.

--
Some informative links:
news:news.annou nce.newusers
http://www.geocities.com/nnqweb/
http://www.catb.org/~esr/faqs/smart-questions.html
http://www.caliburn.nl/topposting.html
http://www.netmeister.org/news/learn2quote.html

[Gregory Pietsch]

The following is an untested quick hack. There's something like this
in FreeDOS edlin 2.5 (available on ibiblio or alt.sources):

#include <string.h>

char *replace_patter n(char *s, char *p, char *np)
{
char *x;
size_t plen, nplen;

if (s == NULL || p == NULL || np == NULL)
return NULL;
x = strstr(s, p);
if (x == NULL)
return NULL;
plen = strlen(p);
nplen = strlen(np);
if (plen != nplen)
memmove(x + nplen, x + plen, strlen(x + plen) + 1);
memmove(x + plen, np, nplen);
return s;
}

/* Gregory Pietsch */

[Keith Thompson]

"Gregory Pietsch" <GK**@flash.net > writes:

The following is an untested quick hack. There's something like this
in FreeDOS edlin 2.5 (available on ibiblio or alt.sources):

#include <string.h>

char *replace_patter n(char *s, char *p, char *np)
{
char *x;
size_t plen, nplen;

if (s == NULL || p == NULL || np == NULL)
return NULL;
x = strstr(s, p);
if (x == NULL)
return NULL;
plen = strlen(p);
nplen = strlen(np);
if (plen != nplen)
memmove(x + nplen, x + plen, strlen(x + plen) + 1);
memmove(x + plen, np, nplen);
return s;
}

You didn't quote the original question, which was:

] How can I replace an occurence of p(a string) in an other string(s) with
] np(new string)..

If you want to post a followup via groups.google.c om, don't use
the broken "Reply" link at the bottom of the article. Click on
"show options" at the top of the article, then click on the
"Reply" at the bottom of the article headers.

I haven't studied the code carefully, but one thing that jumps out is
that it returns NULL if p does not occur in s.

It's not clear from the orginal problem statement whether the
replacement is supposed to be done in place (writing over the previous
contents of s) or in a newly allocated string. Given that the
function returns a char* result, I assume the latter; otherwise it
might as well be a void function. In this case, surely replacing all
occurences of "foo" by "bar" in "hello" should return "hello", not
NULL.

Also, your function overwrites the original contents of s; as I
mentioned, it's not clear whether this violates the requirements.

Finally, you don't allocate any memory. That's ok if you want to
overwrite s *and* if np is no longer than p. Otherwise, you need to
allocate some extra space, and if you don't want to overwrite s you
need to allocate space for the entire result (and document that the
caller is responsible for deallocating it).

--
Keith Thompson (The_Other_Keit h) ks***@mib.org <http://www.ghoti.net/~kst>
San Diego Supercomputer Center <*> <http://users.sdsc.edu/~kst>
We must do something. This is something. Therefore, we must do this.

[Gregory Pietsch]

Keith Thompson wrote:

"Gregory Pietsch" <GK**@flash.net > writes:

The following is an untested quick hack. There's something like this
in FreeDOS edlin 2.5 (available on ibiblio or alt.sources):

#include <string.h>

char *replace_patter n(char *s, char *p, char *np)
{
char *x;
size_t plen, nplen;

if (s == NULL || p == NULL || np == NULL)
return NULL;
x = strstr(s, p);
if (x == NULL)
return NULL;
plen = strlen(p);
nplen = strlen(np);
if (plen != nplen)
memmove(x + nplen, x + plen, strlen(x + plen) + 1);
memmove(x + plen, np, nplen);
return s;
}
You didn't quote the original question, which was:

] How can I replace an occurence of p(a string) in an other string(s) with
] np(new string)..

If you want to post a followup via groups.google.c om, don't use
the broken "Reply" link at the bottom of the article. Click on
"show options" at the top of the article, then click on the
"Reply" at the bottom of the article headers.

I haven't studied the code carefully, but one thing that jumps out is
that it returns NULL if p does not occur in s.

It's not clear from the orginal problem statement whether the
replacement is supposed to be done in place (writing over the previous
contents of s) or in a newly allocated string. Given that the
function returns a char* result, I assume the latter; otherwise it
might as well be a void function. In this case, surely replacing all
occurences of "foo" by "bar" in "hello" should return "hello", not
NULL.

Also, your function overwrites the original contents of s; as I
mentioned, it's not clear whether this violates the requirements.

Finally, you don't allocate any memory. That's ok if you want to
overwrite s *and* if np is no longer than p. Otherwise, you need to
allocate some extra space, and if you don't want to overwrite s you
need to allocate space for the entire result (and document that the
caller is responsible for deallocating it).

As I said, it was a quick hack. Here's one that has a lot of fixes
suggested above.

#include <string.h>
#include <stdlib.h>

char *replace_patter n(char *s, char *p, char *np)
{
char *x, *r;
size_t slen, plen, nplen;

if (s == NULL || p == NULL || np == NULL)
return NULL;
x = strstr(s, p);
if (x == NULL)
return s;
plen = strlen(p);
nplen = strlen(np);
slen = strlen(s);
r = malloc(slen - plen + nplen + 1);
if (r == 0)
abort(); /* Not worried about error conditions */
strcpy(r, s);
if (plen != nplen)
memmove((r + (x - s)) + nplen, x + plen, strlen(x + plen) + 1);
memmove((r + (x - s)) + plen, np, nplen);
return r;
}


--
Keith Thompson (The_Other_Keit h) ks***@mib.org <http://www.ghoti.net/~kst>
San Diego Supercomputer Center <*> <http://users.sdsc.edu/~kst>
We must do something. This is something. Therefore, we must do this.