You are going to write a program that checks to see if a string is a palindrome.

Question

You are going to write a program that checks to see if a string is a palindrome. “A palindrome is a word, phrase, number, or another sequence of characters which reads the same backward as forward, such as madam or race car. Sentence-length palindromes may be written when allowances are made for adjustments of capital letters, punctuation, or word dividers, such as “A man, a plan, a canal Panama!”. “ (Wikipedia) You will use a stack and a queue to determine if a phrase is a palindrome. You will ignore spaces and punctuation. You may use either a c-string or a c++ string. (Hint: You should store characters on the stack and queue to make this easy.)

The stack class is written for you but will need to be modified to use the correct type. You will need to write the queue class. The Node class will need to be changed to work with the stack and queue classes.

***I have the following done but i do not know if my main is working correctly with the queues and stacks.Dont understand how to build the main.Please help.**

#include <iostream>
#include <string>
using namespace std;
class Node
{
private:
Node *link;
char x;
public:
Node ();
Node (string);
void set_link(Node *ptr); //mutator function to set next pointer
Node*get_link(void);//accessor function return next pointer
int compare_data (char );
void process_data(void);
}; //Node class end
Node::Node()//default constructor
{
link=NULL;
x=0;
}
Node::Node(string phrase)
{
link=NULL;
phrase=x;
}

void Node::set_link(Node*ptr)
{
link=ptr;
}
Node*Node::get_link(void)
{
return link;
}


class Queue //Queue class
{
private:
Node*front;
Node*rear;
int count;
public:
Queue();
void enqueue(void);// adds a node to the end of the list
bool dequeue(string p);//removes a node from the front of the queue
bool get_front(void);//Returns item at the front of the queue
bool empty(void);//returns true if queue is empty
};
Queue::Queue()
{
front=NULL;
rear=NULL;
count=0;
}
void Queue::enqueue(void)//adds node to end of list
{
Node*ptr=new Node();//allocates new node
if (front==NULL)
{
front=rear=ptr;
}
else
{
rear->set_link(ptr);
rear=ptr;
}///
count++;//counter
}
bool Queue::dequeue(string p)
{
if(front!=NULL)
{
Node*ptr=front;
delete front;
front=ptr;
}
if(front==NULL)
{ rear=NULL;
count--;
return true;
}else
return false;
}
bool Queue::get_front(void)
{ if(front!=NULL)
return front;
else
return 0;
}
bool Queue::empty(void)
{
if((count=0)||(front==NULL))
return true;
else
return false;
}//end of queue class



class Stack //Stack class
{private:
Node*top;//points to first node in list
int count;//counts number of nodes in list
public:
Stack();
bool push (string);//adds node to top of stack
bool pop ();//removes node from top of stack
bool empty();//returns true if stack empty

};
Stack::Stack()
{
top = NULL;
count = 0;
}
bool Stack::push (string w)
{
bool success = false;
Node*ptr = new Node();
if (ptr!= NULL)
{
if (top!= NULL)
{

ptr->set_link (top);
}
// Set the top equal to the new Node.
top = ptr;
count ++;

success = true;
}
return success;
}
bool Stack::pop ()
{
bool success = false;
Node *temp;
  
if (top != NULL) // if (top) works also
{
// If there is a top, set success to true
success = true;
count --;

temp = top;
// Set the top pointer to the next data
top = top->get_link();
// Delete the former top
delete temp;
}
return success;
};
bool Stack::empty()
{
if (top != NULL)
return false;
else
return true;
}//end of stack
int main()
{
string phrase;
Queue q;
Stack s;
while(true){
if (phrase.compare("-1")==0)
{
cout << "EXIT"<<endl;
break;
}

// Asks the user to enter a line of text.
cout << "Please enter a phrase: ";
getline(cin, phrase,' ');
cout << endl;
// Puts together the line of text and converts the text to lowercase.
for(int i = 0; i < phrase.length(); i++)
{
phrase[i] = tolower(phrase[i]);
}
  
  
s.push(phrase);
q.dequeue(phrase);

// Checks for palindrome.
bool isPalindrome = true;
for(int i = 0; i < phrase.length(); i++)
{
isPalindrome *= phrase[i] == phrase[phrase.length() - 1 - i];
}
if(isPalindrome)
{
cout << phrase<<" is a palindrome"<<endl;
}
else
{
cout << phrase<<" is not a palindrome"<<endl;
}
}
}

Explanation / Answer

The above code is working correctly with queue and stack. The only change you need to first put '' in phrase.compare() so that if user doesn't enters any value it simply prints EXIT and terminates the program and also put the whole block i.e.

if (phrase.compare("")==0)
{
cout << "EXIT"<<endl;
break;
}

after  

cout << "Please enter a phrase: ";
getline(cin, phrase);

so that first time the user is allowed to take input. The modified code from "main function" is mentioned below.

int main()
{
string phrase;
Queue q;
Stack s;
while(true)
{

// Asks the user to enter a line of text.
cout << "Please enter a phrase: ";
getline(cin, phrase);
if (phrase.compare("")==0)
{
cout << "EXIT"<<endl;
break;
}
cout << endl;
// Puts together the line of text and converts the text to lowercase.
for(int i = 0; i < phrase.length(); i++)
{
phrase[i] = tolower(phrase[i]);
}

s.push(phrase);
q.dequeue(phrase);

// Checks for palindrome.
bool isPalindrome = true;
for(int i = 0; i < phrase.length(); i++)
{
isPalindrome *= phrase[i] == phrase[phrase.length() - 1 - i];
}
if(isPalindrome)
{
cout << phrase<<" is a palindrome"<<endl;
}
else
{
cout << phrase<<" is not a palindrome"<<endl;
}
}
}

You need to just make these changes, rest of the code is working fine.

Related Questions

Navigate

• Browse (All)
• Browse Y
• Subjects

Integrity-first tutoring: explanations and feedback only — we do not complete graded work. Learn more.