/* 
  Creating a dynamic array

  example of using realloc() to create a dynamic array in C 
  useful when you need to store string's of varing sizes  
  without having to hardcode. (block of memory on the heap, 
  malloc() and friends) tested with "valgrind"
  
  If the is a better way to do this, bugs, please let me know. 

  Thu Feb 24 18:46:43 CST 2011
  - nocon@darkflame.net 

*/ 


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

int main() {
     char **array = NULL; //dynamic array
     int i; 
     int slen = 0;
     int m_allocated = 0;


     //random strings of any length
     char *strings[] = {
                     "A", "A", "A", "AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA",
                     "AAAAAAAA", "AAAAA", "AAA", "AAAAAAAAAAAA", "AA"
                    };
      
     // since there is no was to pull total num elements 
     // from the dynamic array, we need to keep track 
     int count = 0; 

     //get input array total elements/size (just informational)
     int n_elements = (sizeof(strings)/sizeof(strings[0]));
     int n_size     = sizeof(strings[0]);
     printf("Input array elements: %d\n",n_elements);
     printf("Input array size: %d\n\n",n_size);

     if(n_elements == 0 || n_size == 0) {
       printf("No data, nothing to do.\n");
       return(-1);
     }

      // proccess *strings, dynamically grow **array by asigning contents of *strings
     for(i = 0; i < (sizeof(strings)/sizeof(strings[0])); i++) {
        printf("Element: %d = %s , addr = %p\n",i, strings[i],&strings[i]);

          //get strlen of name + \0 char
          slen += (strlen(strings[i])+1);
          //printf("Total StrLength: %d\n",slen);


          //a lot of calls to realloc() cosumes resources so allocate
          //enough space only when needed
          if(m_allocated <= slen) {
             m_allocated = (slen*8); // should be good enough size ;)   
             printf("Allocating %lu bytes to array\n",(m_allocated * (sizeof(char *))));
             void *tmp = realloc(array,m_allocated * (sizeof(char *))); 
             if(!tmp) {
                 printf("Could not allocate %d bytes to array!\n",m_allocated);
                 return(-1);
             }
             array = tmp;
          } 
          
          array[i] = strings[i];
          count++; 
     }

     //print array 
     printf("\n\n"); 
     for(i = 0; i < count; i++) {
        printf("Element: %d = %s , addr = %p\n",i, array[i],&array[i]);
     }      

   printf("\n\n"); 

  // all done, be free!!
  free(array); 

 return 1;
}