Question

I am practicing using stack with c++. Objective of the program is to ask a user to input a series of letters, seperate it by $. See if they are symmetrical

So for instance, if abc$cba would make it work. Although if it were sabc$cba would be false because s is not symmetrical and does not match.

I am running into a bug where if I try to input letters that do not contain an $ and are in a group of odd numbers, such as 3 or 5, then the program will just bug out. ie "aaa" or "aaaaa." I need to find a solution that'll return false if the string does not contain an $ and is odd numbered amount of letters.

source: https://pastebin.com/LsimEmeC

header: https://pastebin.com/yrXndpDr

Answer 1

//In Language Problem

#include<iostream>
#include"Stack.h"
#include<string>
using namespace std;

bool checkIt_1(string s)
{
   bool b = true;
   Stack<char> myStack;
   int stringLength = s.length();
   int i;
   for (i = 0; i<stringLength; i++) {
       if (s.at(i) != '$')
           myStack.push(s.at(i));
       else
           break;
   }
   if (i == stringLength)
       b = false;
   else {
       while (!myStack.isEmpty() || i<stringLength - 1) {
           if (myStack.isEmpty() && i<stringLength - 1) {
               b = false;
               break;
           }
           else if (!myStack.isEmpty() && i == stringLength - 1) {
               b = false;
               break;
           }
           else if (myStack.peek() != s.at(++i)) {
               b = false;
               break;
           }
           else
               myStack.pop();
       }
   }
   return b;
}

bool checkIt_2(string s)
{
   Stack<char> myStack; // declare myStack as char
   int stringLength = s.length();
   if(stringLength % 2 == 1 && s.find('$') == -1) {
       return false;
   }
   if (stringLength == 0 || stringLength % 2 == 0) { // if length is even or has 0 characters, return false
       return false;
   }
   else {
       if (stringLength == 1) { //if character only has one length, and is $, return true. else false.
           if (s.at(0) == '$')
               return true;
           else
               return false;
       }
       else {
           //Pushing characters on the left side of $
           int i = 0;
           while (s.at(i) != '$' || (i < stringLength/2) && i<stringLength) { // as long as not $, push stack - checks length of string to keep it from going on forever
               //when looking for $
               myStack.push(s.at(i));
               i++;
           }
           // Now out of while loop,
           //either seen $ or reached the end of string with no $
           if (i == stringLength)
               return false;
           else {
               i++; //skips the $ in the string
               if (i == stringLength)
                   return false; //when the $ is at the end of the string
               else {
                   while (!myStack.isEmpty() && i != stringLength) {
                       if (myStack.peek() == s.at(i)) { //compares, if same, pop
                           myStack.pop();
                           i++;
                       }
                       else
                           return false;
                   }
                   //When we get out of while loop, either
                   //1. !myStack.isEmpty() has failed -> The stack is empty
                   //or
                   //2. i! stringlength has failed -> i==stringLength -> reached end of string
                   //or
                   //3. Both !myStack.isEmpty() and i==stringLength have failed -> Stack is empty and we reaached
                   //the end of the string.
                   if (myStack.isEmpty() && i == stringLength)
                       return true;
                   else
                       return false;
               }
           }
       }

   }
}

int main()
{
   string testString;
   cout << "Please enter a string:\n";
   cin >> testString;
   if (checkIt_2(testString))
       cout << "It is in the language!\n";
   else
       cout << "It is not in the language!\n";

   system("pause");
   return 0;
}

lease enter a string: It is not in the language! Press any key to continue . - . Process exited after 2.345 seconds with returnvalue 0 Press any key to continue . - .