C, REGEX

learn regular expression in C
info:
http://www.opengroup.org/onlinepubs/007908799/xsh/regex.h.html

#include <regex.h>

structuren:

regex_t preg;
regmatch_t pmatch[100];

example: regex1.c
#################################################

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


int main() {

  int err;
  char err_str[200];
  char results[500];

  int i,j,k=0;

  regex_t preg;
  regmatch_t pmatch[100];

  char *buf="blub blub blub@googlemail.com adslfku asdf@gmail.com oasduf";

  if( (err = regcomp(&preg, "\\b[A-Za-z0-9._%+-]+@(gmail|googlemail)+\\.[a-zA-Z]{2,4}\\b", REG_EXTENDED)) != 0)  {
    printf("regcomp error\n");
    return -1;
  }

  if( (err = regexec(&preg, buf, preg.re_nsub, pmatch, 0)) != 0)  {
    regerror(err, &preg, err_str, 200);
    printf("%s\n",err_str);
    return -1;
  } else {
    for(i = 0; i < preg.re_nsub; i++) {
      if(pmatch[i].rm_so == -1) continue;
      for(j = pmatch[i].rm_so; j < pmatch[i].rm_eo; j++) 
        results[k++] = buf[j];
      results[k] = '|';
      results[++k] = '\0';
    }
  }
  printf(">> results: %s\n", results);
  regfree(&preg);
return 0;
}

#################################################

"\\b[A-Za-z0-9._%+-]+@(gmail|googlemail)+\\.[a-zA-Z]{2,4}\\b": example pattern
regcomp(): compile the seek string (pattern)
regexec(): seek for a pattern in string

struct regmatch_t

typedef struct
{
  regoff_t rm_so;  /* Byte offset from string's start to substring's start.  */
  regoff_t rm_eo;  /* Byte offset from string's start to substring's end.  */
} regmatch_t; 

further functions:
regerror(): error handling
regfree (): free buffers