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

/*
** --------------------------------------------------------------------------
**
** tokenizeEX
**
** Returns a 'const char *' pointing to the next token or NULL
** if no more tokens were found.
**
**    theString    - string to be tokenized
**
**    stringLength - length of 'theString'
**
**    delimiters   - the separator characters
**
**    pOffset      - pointer to the current offset (0, 1, 2, ...) within
**                   'theString',  should be set to 0 before the first
**                   call to this function and will from then onward
**                   but updated automatically.
**
**    pLength      - the length of the token returned
**
** --------------------------------------------------------------------------
*/

static const char *tokenizeEX(
   const char *theString,
   int        stringLength,
   const char *delimiters,
   int        *pOffset,
   int        *pTokenSize
)
{
   const char *ptr = NULL;

   if(theString && delimiters && *pOffset < stringLength)
   {
      int i = *pOffset;

      while(i < stringLength && strchr(delimiters, theString[i]))
         i++;

      if(i < stringLength)
      {
         int j = i + 1;

         while(j < stringLength)
         {
            if(strchr(delimiters, theString[j]))
               break;

            j ++;
         }

         *pOffset    = j;
         *pTokenSize = (j - i);

         ptr = theString + i;
      }
   }

   return(ptr);
}

/*
** --------------------------------------------------------------------------
**
** tokenize
**
** Returns a 'const char *' pointing to the next token or NULL
** if no more tokens were found.
**
**    theString    - string to be tokenized
**
**    delimiters   - the separator characters
**
**    pOffset      - pointer to the current offset (0, 1, 2, ...) within
**                   'theString',  should be set to 0 before the first
**                   call to this function and will from then onward
**                   will be updated automatically
**
**    pLength      - the length of the token returned
**
** --------------------------------------------------------------------------
*/

static const char *tokenize(
   const char *theString,
   const char *delimiters,
   int        *pOffset,
   int        *pTokenSize
)
{
   return(
      tokenizeEX(
         theString, strlen(theString), delimiters, pOffset, pTokenSize
      )
   );
}

/******************
 * exampleOne
 ******************/

static void exampleOne()
{
   const char *theString = "2, 3, 5, 7, 11, 13, 17, 19, 23, 29";
   const char *token     = NULL;
   int offset            = 0;
   int length            = 0;

   printf("exampleOne: [%s]\n", theString);

   while((token = tokenize(theString, ", ", &offset, &length)) != NULL)
      printf("[%.*s]\n", length, token);

   printf("\n");
}

/******************
 * exampleTwo
 ******************/

static void exampleTwo()
{
   const char *theString =
      "127.0.0.1 4.3.2.1 100.200.300.400";

   const char *tokenOuter  = NULL;
   int         offsetOuter = 0;
   int         lengthOuter = 0;

   printf("exampleTwo: [%s]\n", theString);

   while((tokenOuter = tokenize(theString, " ", &offsetOuter, &lengthOuter)) != NULL)
   {
      const char *tokenInner  = NULL;
      int         offsetInner = 0;
      int         lengthInner = 0;

      printf("[%.*s]\n", lengthOuter, tokenOuter);

      /* -- Because 'tokenOuter' is not null terminated, we must
            supply its length manually and use tokenizeEX -- */

      while((tokenInner = tokenizeEX(tokenOuter, lengthOuter,
         ".", &offsetInner, &lengthInner)) != NULL)
            printf(" [%.*s]\n", lengthInner, tokenInner);
   }

   printf("\n");
}

/******************
 * exampleThree
 ******************/

static void exampleThree()
{
   const char *theString =
      "a, b, 'c, d, e', f, 'g, h, i, j, k'";

   const char *token  = NULL;
   int         offset = 0;
   int         length = 0;

   printf("exampleThree: [%s]\n", theString);

   while((token = tokenize(theString, "'", &offset, &length)) != NULL)
   {
      char buffer[255] = { 0 };

      int offsetInner = 0;
      int lengthInner = 0;

      /* -- By copying to 'buffer', our string will be null terminated
            so we don't need to use tokenizeEX, we can use tokenize -- */

      snprintf(buffer, sizeof(buffer), "%.*s", length, token);

      printf("[%s]\n", buffer);

      while((token = tokenize(buffer, ", ", &offsetInner, &lengthInner)) != NULL)
         printf(" [%.*s]\n", lengthInner, token);
   }
}

/******************
 * main
 ******************/

int main()
{
   exampleOne();
   exampleTwo();
   exampleThree();

   return(0);
}