Question

Stack

1. Create a New Project and give your project a name, say.
2. Download the given source files StackArr.h and StackArr.cpp from Moodle and save them to your Lab6a folder. Also import them to your project.
3. Add a source file to your project, called StackMain.cpp and implement your program according to the following:
   1. Prompt the user to input a program filename.
   2. Open the file and check if every right brace (i.e. }), bracket (i.e. ]), and parenthesis (i.e. )) in the file correspond to its left counterpart or not.
   3. If the program file passed the checking, output "The code is correct". Otherwise, output "The code is incorrect".

The algorithm for checking is as follows:

1. Make an empty stack
2. Read characters until the end of program file
   1. if the character is an opening symbol, push it onto the stack;
   2. if it is a closing symbol and if the stack is empty, output "Error: Empty stack";
   3. otherwise, pop the stack. If the symbol popped is not the corresponding opening symbol, output "Error: Not equal".

At the end of the file, if the stack IS NOT EMPTY, output "The code is incorrect". Otherwise, output "The code is correct".

Code below:

//////////////////////////////////StackArr.h////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////

#ifndef STACKARR_H
#define STACKARR_H

class StackArr {
private:
   int maxTop;
   int stackTop;
   char *values;

public:
   StackArr(int);
   ~StackArr();
   bool isEmpty() const;
   bool isFull() const;
   char top() const;
   void push(const char& x);
   char pop();
   void displayStack() const;
};

#endif
#pragma once

//////////////////////////////////StackArr.cpp////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////

#include "StackArr.h"
#include <string>
#include <iostream>

using namespace std;

StackArr::StackArr(int size) {
   maxTop = size;
   values = new char[size];
   stackTop = -1;
}

StackArr::~StackArr() {
   delete[] values;
}

bool StackArr::isEmpty() const {
   return stackTop == -1;
}

bool StackArr::isFull() const {
   return stackTop == maxTop;
}

void StackArr::push(const char& x) {
   if (isFull())
       cout << "Error! The stack is full!" << endl;
   else
       values[++stackTop] = x;
}

char StackArr::pop() {
   if (isEmpty()) {
       cout << "Error! The stack is empty!" << endl;
       return -1;
   }
   else
       return values[stackTop--];
}

char StackArr::top() const {
   if (isEmpty()) {
       cout << "Error! The stack is empty!" << endl;
       return -1;
   }
   else
       return values[stackTop];
}

void StackArr::displayStack() const {
   cout << "Top -->";
   for (int i = stackTop; i >= 0; i--)
       cout << "\t|\t" << values[i] << "\t|" << endl;
   cout << "\t|---------------|" << endl << endl;
  
}

Answer 1

Hi there,

I have completed the code as per your requirements. I have made some changes to your above starter files as they were writing unwanted output to the terminal.

The code:

#include "StackArr.h"
#include <string>
#include <iostream>
#include <fstream>

using namespace std;

StackArr::StackArr(int size) {
maxTop = size;
values = new char[size];
stackTop = -1;
}

StackArr::~StackArr() {
delete[] values;
}

bool StackArr::isEmpty() const {
return stackTop == -1;
}

bool StackArr::isFull() const {
return stackTop == maxTop;
}

void StackArr::push(const char& x) {
if (isFull())
cout << "Error! The stack is full!" << endl;
else
values[++stackTop] = x;
}

char StackArr::pop() {
if (isEmpty()) {
return -1;
}
else
return values[stackTop--];
}

char StackArr::top() const {
if (isEmpty()) {
return -1;
}
else
return values[stackTop];
}

void StackArr::displayStack() const {
cout << "Top -->";
for (int i = stackTop; i >= 0; i--)
cout << "\t|\t" << values[i] << "\t|" << endl;
cout << "\t|---------------|" << endl << endl;
  
}
//Code starts
int main()
{
   ifstream infile;
   string file;
   cout<<"Please enter the file name : ";
   cin>>file;
   //opening the file
    infile.open(file);
    //check if file exists or not
    if (!infile.is_open())
    {
        cout<<"\nFile did not open!! please try again...\n";
        exit(0);
    }
    char ch;
    //create the stack
    StackArr st = StackArr(100);
    //bool to track if the code is correct or not
    bool correct=true;
    //read the file character by character
    while(infile.get(ch))
    {
        //if it is a opening bracket
        if(ch=='(' || ch=='{' || ch=='[')
            st.push(ch);
        //if it is a closing bracket     
        if(ch==')' || ch=='}' || ch==']')
        {
            //if the closing bracket matches the opening bracket
            if(!st.isEmpty() && (ch==')' && st.top() == '(') || (ch=='}' && st.top() == '{') || (ch==']' && st.top() == '['))
              st.pop();
          else
          {
              correct = false;
              break;
          }
      }
   }
   if(!correct)
   {
      cout<<"\nError: Not equal";
   }
   else if(!st.isEmpty())
      cout<<"\nThe code is incorrect";
   else
      cout<<"\nThe code is correct";
   cout<<"\n";
   //close the file
   infile.close();
   return 0;
}                         

The Code(screenshot) :   

The test file(Screenshot) :   

The Output(Screenshot) :

Hope you liked my answer. If you have any doubts, please feel free to ask in the comment section.

Happy Coding :)