C Libriaries for string

alaios · 04-30-2012, 12:28 AM

Dear all,
I would like to ask you if you know any web site that has a lit of c libraries/functions especially for strings.

I would like to have a good reference when I want to do something with strings and try to answer a question of the form "I need a function that finds in hug string a filename of the format *.html"

Do you know anything like that?

I would like to thank you in advance for your help

B.R
Alex

flamelord · 04-30-2012, 01:43 AM

http://www.cplusplus.com/reference/clibrary/cstring/
http://www.utas.edu.au/infosys/info/....html#string.h
http://en.wikipedia.org/wiki/String.h

man page for string.h

for regular expressions:

man regex.h
http://www.gnu.org/software/libc/man...pressions.html

google search for things like "c string" "c string.h" "c regular expression" "c regex.h", stuff like that. That's how I found the above links.

Sergei Steshenko · 04-30-2012, 03:20 PM

Quote:

Originally Posted by alaios

... I need a function that finds in hug string a filename of the format *.html ...

I am not sure I understand you, but if you need to make queries whether something is present in an HTML file, you need and HTML parser - not a "C" string library.

alaios · 05-01-2012, 07:24 AM

Thats a small part of my code.... I want to get out of that string the index.html and or the test.html

Unfortunately it returns no match...

What might I doing wrong here?

Regards
Alex

Code:

/*
** talker.c -- a datagram "client" demo
*/

#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <errno.h>
#include <string.h>
#include <sys/types.h>
#include <regex.h>

int main(int argc, char *argv[])
{
	int i,reti;
	regex_t regex;
	reti = regcomp(&regex, ".*\.\(html\|htm\)", 0);
	char errormsg[100];
	if( reti )
		{ fprintf(stderr, "Could not compile regex\n");
		   exit(1);
		}
 


        reti = regexec(&regex, "I am looking inside this string the index.html or any other files in this format like test.html", 0, NULL, 0);
        if( !reti ){
                       printf("Match\n");
               	   }
       else if( reti == REG_NOMATCH ){
    	   	   printf("No match\n");
    	   	   regerror(reti,&regex,errormsg,sizeof(errormsg));
    	   	   printf("error text is: %s\n",errormsg);
    	   }
       




    return 0;
}

Sergei Steshenko · 05-01-2012, 08:15 AM

Quote:

Originally Posted by alaios

Thats a small part of my code.... I want to get out of that string the index.html and or the test.html

Unfortunately it returns no match...

What might I doing wrong here?

Regards
Alex

Code:

/*
** talker.c -- a datagram "client" demo
*/

#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <errno.h>
#include <string.h>
#include <sys/types.h>
#include <regex.h>

int main(int argc, char *argv[])
{
	int i,reti;
	regex_t regex;
	reti = regcomp(&regex, ".*\.\(html\|htm\)", 0);
	char errormsg[100];
	if( reti )
		{ fprintf(stderr, "Could not compile regex\n");
		   exit(1);
		}
 


        reti = regexec(&regex, "I am looking inside this string the index.html or any other files in this format like test.html", 0, NULL, 0);
        if( !reti ){
                       printf("Match\n");
               	   }
       else if( reti == REG_NOMATCH ){
    	   	   printf("No match\n");
    	   	   regerror(reti,&regex,errormsg,sizeof(errormsg));
    	   	   printf("error text is: %s\n",errormsg);
    	   }
       




    return 0;
}

Start from a simpler case, i.e. try to match 'a' in "a".
...
Maybe you need double backslashes.
...
You are doing it apparently wrong - as I wrote earlier in this thread, you need and HTML parser.

alaios · 05-01-2012, 10:00 AM

I do no want any html parser this is an example when I have a given string

I am looking inside this string the index.html or any other files in this format like test.html

to get back only the index.html

Sergei Steshenko · 05-01-2012, 10:19 AM

Quote:

Originally Posted by alaios

I do no want any html parser this is an example when I have a given string

I am looking inside this string the index.html or any other files in this format like test.html

to get back only the index.html

You have probably modified this: http://www.peope.net/old/regex.html :

Code:

#include <sys/types.h>
#include <regex.h>
#include <stdio.h>

int main(int argc, char *argv[]){
        regex_t regex;
        int reti;
        char msgbuf[100];

/* Compile regular expression */
        reti = regcomp(&regex, "^a[[:alnum:]]", 0);
        if( reti ){ fprintf(stderr, "Could not compile regex\n"); exit(1); }

/* Execute regular expression */
        reti = regexec(&regex, "abc", 0, NULL, 0);
        if( !reti ){
                puts("Match");
        }
        else if( reti == REG_NOMATCH ){
                puts("No match");
        }
        else{
                regerror(reti, &regex, msgbuf, sizeof(msgbuf));
                fprintf(stderr, "Regex match failed: %s\n", msgbuf);
                exit(1);
        }

/* Free compiled regular expression if you want to use the regex_t again */
	regfree(&regex);

        return 0;
}

example.

Does the original non-modified example work ?

flamelord · 05-01-2012, 11:55 AM

I'm not entirely sure why what you have doesn't work but if you change the regcomp line to

Code:

	reti = regcomp(&regex, ".*\.(html|htm)", REG_EXTENDED);

it seems to work (the trick is the REG_EXTENDED option)

alaios · 05-01-2012, 03:06 PM

The following brought me slightly closer

Code:

#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <errno.h>
#include <string.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <arpa/inet.h>
#include <netdb.h>
#include <regex.h>

int main(int argc, char *argv[])
{
	int i,reti;
	size_t nmatch=10;
	regex_t regex;
	reti = regcomp(&regex, "[^\.]*", REG_EXTENDED);
	char errormsg[100];
	regmatch_t pmatch[nmatch];
	char *string="I am looking inside this string the index.html or any other files in this format like test.htm";
	if( reti )
		{ fprintf(stderr, "Could not compile regex\n");
		   exit(1);
		}

    else{
    	printf("socket created %d",i);


        reti = regexec(&regex, string, nmatch, pmatch, 0);
        if( !reti ){
                       printf("Match\n");
                       printf("With the whole expression, "
                                    "a matched substring \"%.*s\" is found at position %d to %d.\n",
                                    pmatch[0].rm_eo - pmatch[0].rm_so, &string[pmatch[0].rm_so],
                                    pmatch[0].rm_so, pmatch[0].rm_eo - 1);
                             printf("With the sub-expression, "
                                    "a matched substring \"%.*s\" is found at position %d to %d.\n",
                                    pmatch[1].rm_eo - pmatch[1].rm_so, &string[pmatch[1].rm_so],
                                    pmatch[1].rm_so, pmatch[1].rm_eo - 1);
               	   }
       else if( reti == REG_NOMATCH ){
    	   	   printf("No match\n");
    	   	   regerror(reti,&regex,errormsg,sizeof(errormsg));
    	   	   printf("error text is: %s\n",errormsg);
    	   }
       }


    regfree(&regex);

    return 0;
}

but returning the

Code:

socket created 32767Match
With the whole expression, a matched substring "I am looking inside this string the index" is found at position 0 to 40.
With the sub-expression, a matched substring "" is found at position -1 to -2.

In the give regular expression I try to get only index (from the index.html), well in the ideal case I want to have the "index.html" but I have simplified it a bit.

As you can see it seems to find something but the returned positions seem weird...

flamelord · 05-01-2012, 03:16 PM

You're current regular expression is matching any string which doesn't contain any periods. I think you want a regular expression like: "(\\w*)\\.htm", this matches the whole string "index.htm" and the first subexpression is just "index", the \\'s are to escape the backslashes so C doesn't interpret them, and "\w" is the character class for word characters (i.e. [A-Za-z0-9])

alaios · 05-02-2012, 01:06 AM

That solved my problem. I only changed the regex... kaboom finished

Great now I will try to further improve it.