Thread: Need suggestions on elegant use of string and stdlib libraries.

strtoke returns a pointer to the first character of the part of the string that was delimited by '\0'.
The elegant way is to use that pointer.
And as ( and ) are concerend, the elegant way is strchr, and strrchr.

Code:

char *c;
c = strchr(yourString, '(');
yourString = c;
c = strrchr(yourString, ')');
*c = '\0';

yourString should now not have any left and right parentheses.

strtok can take multiple delimiters.

Code:

#include <stdio.h>
#include <string.h>

int main()
{
   char phoneNum[] = "(404) 993-2241";
   char *str = phoneNum;
   char *token;
   while ( (token = strtok ( str, " ()-" )) )
   {
      puts(token);
      str = 0;
   }
   return 0;
}

/* my output
404
993
2241
*/

But if you REALLY want to verify a telephone number, it's probably better to write a piece of code that checks that EACH portion is entirely correct, with the right number of digits, separators in the right place etc. As a side-effect, it may split the number into areacode and phone number. For REAL checking, you should also consider checking that the area code is valid [I beleive there is a simple method by checking that the second digit is a 0 or a 1, but I could have that wrong].

Edit: At least the task is easier with US phone numbers than with many european countries, where phone numbers vary in length depending on the area code, and sometimes even within an area [based on the first digit after the area code, in general]. I wrote a verifier for Swedish telephone numbers once.

--
Mats

It comes to a point when the phrase Regular Expressions might be a good hint towards a good solution, if the input is to be 100% verified.

Code:

#include <regex.h>
#include <stdio.h>
#include <stdlib.h>

int main()
{
        /* Regular expression to match a US phone number */
        char phonePattern[] = "[(]([0-9]{3})[)] ([0-9]{3})-([0-9]{4})";
        char testS[] = "For more information call (345) 123-4567.";
        regmatch_t *found;
        regex_t regx;

        /* Compile the expression in phonePattern to a regex_t */
        regcomp(&regx, phonePattern, REG_EXTENDED);

        /* Allocate memory for the bracketed parts of the expression */
        found = malloc( (regx.re_nsub+1) * sizeof(*found) );
        if( regexec(&regx, testS, regx.re_nsub + 1, found, 0) == 0 )
        {
                int i;
                /* At found[0] the indices for the entire match are stored 
                 * so, if we don't need it we better start of found[1] 
                 */
                for(i = 1; i <= regx.re_nsub; i++)
                {
                        printf("Piece of phone #%d: <", i);
                        fwrite(testS+found[i].rm_so, 1, found[i].rm_eo - found[i].rm_so, stdout);
                        printf(">\n");
                }
        }
        free(found);

        return 0;
}

The non standard POSIX compliant <regex.h> header usually comes with a typical installation of gcc.
For a Regular Expression library that is free and ported for Windows, one can always get it from:
http://www.pcre.org/

Code:

#include <regex.h>

For nonstandard stuff, could you please mention the additional things that are necessary to the code work?