// This program demonstrates a recursive function for counting
// the number of times a character appears in a string.
#include <iostream>
using namespace std;

// Function prototype
int numChars(char, char [], int);

int main()
{
   char array[] = "abcddddef";
   
   // Display the number of times the letter
   // 'd' appears in the string.
   cout << "The letter d appears "
        << numChars('d', array, 0) << " times.\n";

   return 0;
}
   
//************************************************
// Function numChars. This recursive function    *
// counts the number of times the character      *
// search appears in the string str. The search  *
// begins at the subscript stored in subscript.  *
//************************************************

int numChars(char search, char str[], int subscript) 
{ 
   if (str[subscript] == '\0')
   {
      // Base case: The end of the string is reached. 
      return 0;
   }
   else if (str[subscript] == search) 
   {
      // Recursive case: A matching character was found.
      // Return 1 plus the number of times the search
      // search appears in the rest of the string.
      return 1 + numChars(search, str, subscript+1); 
   }
   else 
   {
      // Recursive case: A character that does not match the
      // search character was found. Return the number of times
      // the search character appears in the rest of the string.
      return numChars(search, str, subscript+1); 
   }
}