/*
Programmer:	Greg Perkins
Program:		letter_count.c
Class:		CS 73 C/UNIX
Due:			12 February 1998

This program accepts data from standard input and reports the number
of times that letters are repeated.  It outputs the number of times
repeated characters occurred.  A character is counted as repeated even
if whitespace or punctuation falls between it and the next occurrence
of the letter.  The character is not counted as repeated when other
alphanumeric characters follow it.
*/

#include <stdio.h>
#include <ctype.h>

int main()
{
	int count = 0;
	int new_char, prev_char = -999;	/* -999 indicates first character */

	while ((new_char = getchar()) != EOF)
	{
		/* consider upper & lowercase letters as equal */
		if (isalpha(new_char))
			new_char = tolower(new_char);

		if (prev_char != -999)		/* if past first character */
		{
			/* if new_char is not whitespace or punctuation check repeat */
			if(isalnum(new_char))
				if (new_char == prev_char)
					count++;
				else
					prev_char = new_char;
		}
		else
			prev_char = new_char;
 	}

	printf("\nThe number of repeated characters was %d.\n", count);

	return (0);
}