String Permutation Lexicographically in C

StringPermLexico.c

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

/* Following function is used by the library qsort() function to sort an array of chars */
int compare (const void * a, const void * b);

/* this function recursively prints all repeated permutations of the given string.*/
void LRecurse (char *str, char* data, int last, int index)
{
   int i, len = strlen(str);

   // One by one fix all characters at the given index and recur for the subsequent indexes
   for ( i=0; i<len; i++ )
   {
       // Fix the ith character at index and if this is not the last index then recursively call for higher indexes
       data[index] = str[i] ;

       // If this is the last index then print the string stored in data
       if (index == last)
           printf("%s\n", data);
       else
           LRecurse (str, data, last, index+1);
   }
}

/* This function sorts input string, allocate memory and calls LRecurse() for printing all permutations */
void LSort(char *str)
{
   int len = strlen (str) ;
 
   char *data = (char *) malloc (sizeof(char) * (len + 1)) ;
   data[len] = '\0';
   
   // Sort the input string so that we get all output strings in lexicographically sorted order
   qsort(str, len, sizeof(char), compare);
   LRecurse (str, data, len-1, 0);
   free(data);// Free data to avoid memory leak
}

// Needed for library function qsort()
int compare (const void * a, const void * b)
{
   return ( *(char *)a - *(char *)b );
}

int main()
{
   char str[] = "GOD";
   printf("All permutations of %s in Lexicographic order are : \n", str);
   LSort(str);
   getchar();
   return 0;
}