Try to use regular expression in C for searching UTF-8 Thai string by calling Onigmo

oni1.c

/*
 *
 * Copyright (c) 2016 Vee Satayamas
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 *
 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 *
 */

/* 
 * 
 * How to build:
 * gcc -Wall -g oni1.c -lonig
 *
 ********************************************
 *
 * What is needed?
 * Onigmo (libonig)
 *
 * libonig on Debian/Ubuntu can be installed by apt-get install libonig-dev
 *
 */

#include <stdio.h>
#include <oniguruma.h>

void
display_region(OnigRegion *region)
{
  int i;
  for (i = 0; i < region->num_regs; i++)
    {
      printf("%d...%d\n", region->beg[i], region->end[i]);
    }
}

int
main(int argc, char **argv)
{
  regex_t *reg;
  OnigErrorInfo e_info;
  UChar *pat = (UChar *)"[0-9]+";
  UChar *str = (UChar *)"กา2559บิน";
  OnigEncoding enc = ONIG_ENCODING_UTF8;
  int r;
  unsigned char *start, *end, *range;
  OnigRegion *region;
  int r_search;

  r = onig_new(&reg,
	       pat,
	       pat + onigenc_str_bytelen_null(enc, pat),
	       ONIG_OPTION_NONE,
	       enc,
	       ONIG_SYNTAX_DEFAULT,
	       &e_info);

  if (r != ONIG_NORMAL)
    {
      char s[ONIG_MAX_ERROR_MESSAGE_LEN];
      onig_error_code_to_str(s, r, &e_info);
      fprintf(stderr, "ERROR: %s\n", s);
      return -1;
    }
  end = str + onigenc_str_bytelen_null(enc, str);
  region = onig_region_new();
  start = str;
  range = end;
  r_search = onig_search(reg,
			 str,
			 end,
			 start,
			 range,
			 region,
			 ONIG_OPTION_NONE);

  if (r_search >= 0)
    {
      printf("MATCH:\n");
      display_region(region);
    }
  else if (r_search == ONIG_MISMATCH)
    {
      printf("MISMATCH\n");
    }
  else
    {
      fprintf(stderr, "ERROR\n");
      return -1;
    }
  
  onig_region_free(region, 1);
  onig_free(reg);
  onig_end();
  return 0;
}