Palindrome Stack and Queue

[Lacy9265]

The idea of this assignment is to use both a stack and a queue to implement a palindrome-recognition. I have finished this code. However, I wanted to get feedback to make sure I did this assignment correctly. Please let me know of any concerns or idea that will help me with this assignment. Also, did I implement the stack and queue correctly for this assignment. The code includes a driver.cpp, driver.h, and palindrome.cpp.

// driver.cpp
#include <string>
#include <iostream>
#include "Driver.h"

int main() {

	// Declare variables
	std::string text = " ";
	

	// Have user enter text for palindrome
	std::cout << "Enter text: ";
	std::getline(std::cin, text);
	std::cout << std::endl;


	// Call on isPalindrome method to see if the text entered is one
	if (!isPalindrome(text)) {
		std::cout << "The text you entered is not a palindrome.";  // not a palindrome
	}
	else {
		std::cout << "The text you entered is a palindrome.";  // is a palindrome
	}

}

// driver.h
#include <string>
#include <iostream>


// Palindrome method tells whether the string is a palindrome
bool isPalindrome(std::string str);



// palindrome.cpp
#include <string>
#include <queue>
#include <stack>
#include <iostream>
#include "Driver.h"

// ----------------------------------------------------------------------
// isPalindrome: Whether the given string is a palindrome
// string str: is the user entered text
// returns what whenever the characters for the string are true or false
// ----------------------------------------------------------------------
bool isPalindrome(std::string str) {
	// Declare variables
	int length;
	char nextCharacter;
	bool charactersEqual;
	char queueFront;
	char stackTop;
	

	// Create an empty queue and stack
	std::queue<char> queue;
	std::stack<char> stack;

	// Set lenth to length of string 
	length = str.length();

	// Add each character of string to both queue and stack
	for (int i = 0; i < length; i++) {
		nextCharacter = str.at(i);
		queue.push(nextCharacter);
		stack.push(nextCharacter);

	}
	// Set characters to true
	charactersEqual = true;
	
	// Compare queue characters with stack characters
	while (!queue.empty() && charactersEqual) {
		queueFront = queue.front();
		stackTop = stack.top();

		if (queueFront == stackTop) {
			queue.pop();
			stack.pop();
		}
		else {
			charactersEqual = false;
		}
	}
	return charactersEqual;  // return characters that are equal

}

[seeplus]

[Also here http://www.cplusplus.com/forum/beginner/278612/ ]

Well the code will work - but see my previous answers in the above thread.

[lastchance]

I guess it depends whether you think "Abba" is palindromic or not.

You are also comparing twice as many characters as you need to in order to determine palindromicity: you only need to consider the first N/2, not empty the containers. (The same is true of comparing a string with the whole of its reverse.)

[Lacy9265]

Just trying to see if I used the queue and stack properly. In some examples of the queue I have found they use Empty(), enqueuer(), dequeuer(), and peekFront(). This is first time writing code that use both the stack and queue to implement something

[lastchance]

In some examples of the queue I have found they use Empty(), enqueuer(), dequeuer(), and peekFront()

Time to write C++, not Java. None of those are standard library functions. Goodness knows where you got your "examples" from.

You missed the gist of both comments in my post.

[seeplus]

Re lastchance's second point. The while test in L77 could be:

while (queue.size() > length / 2 && charactersEqual) {

to eliminate unnecessary comparisons. But as per my other post, the code can be 'simplified':

bool isPalindrome(const std::string& str) {
	std::queue<char> queue;
	std::stack<char> stack;

	// Add each character of string to both queue and stack
	for (const char c : str) {
		queue.push(c);
		stack.push(c);
	}

	// Set characters to true
	bool charactersEqual {true};

	// Compare queue characters with stack characters
	while (queue.size() > str.size() / 2 && charactersEqual)
		if (queue.front() == stack.top()) {
			queue.pop();
			stack.pop();
		} else
			charactersEqual = false;

	return charactersEqual;  // return characters that are equal
}

or even:

bool isPalindrome(const std::string& str) {
	std::queue<char> queue;
	std::stack<char> stack;

	// Add each character of string to both queue and stack
	for (const char c : str) {
		queue.push(c);
		stack.push(c);
	}

	// Compare queue characters with stack characters
	for (; queue.size() > str.size() / 2; queue.pop(), stack.pop())
		if (queue.front() != stack.top())
			return false;

	return true;  // return characters that are equal
}

which slightly changes the algorithm.