//
// Program name:  palindrome
// Author:  B. Massingill
//
// Input:  a sequence of characters, ended by ctrl-D (end of file)
// Output:  a message saying whether the input forms a palindrome
//
#include <iostream.h>
#include <ctype.h>		// for character library functions
//
// Function name:  isPalindrome
//
// Precondition:
//	phrase contains phraseLength characters that we want to
//		check -- do they form a palindrome?
// Postcondition:
//	return value is true if the characters form a palindrome,
//		false otherwise
//
// Note that the test skips all but alphabetic characters and is
//	not case-sensitive.
//
bool isPalindrome(char phrase[], int phraseLength) ;
//
// main program
//
int main()
{
	const int MAXLEN = 100 ;
	char inchars[MAXLEN] ;
	char tempchar ;
	int numchars = 0 ;
	cout << "Enter a phrase, ctrl-D to end\n" ;
	while (cin.get(tempchar))
	{
		if (numchars >= MAXLEN)
		{
			cout << "Too long!\n" ;
			return -1 ;
		}
		inchars[numchars++] = tempchar ;
	}
	if (isPalindrome(inchars, numchars))
		cout << "It's a palindrome\n" ;
	else
		cout << "It's not a palindrome\n" ;

	return 0 ;
}
// function definition -- see prototype above for documentation
bool isPalindrome(char phrase[], int phraseLength) 
{
	int left = 0 ;			// leftmost character not
					//	yet compared
	int right = phraseLength - 1 ;	// rightmost character not
					//	yet compared
	bool result = true ;
	while (result && left < right) 
	{
		if (!isalpha(phrase[left])) 
			left += 1 ;
		else if (!isalpha(phrase[right]))
			right -= 1 ;
		else
			result = tolower(phrase[left++]) == tolower(phrase[right--]) ;
	}
	return result ;
}