Question

Part 1: Stack

1. Create a New Project and give your project a name, say Lab6a.
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".

Use the provided files, testfile1.txt and testfile2.txt to test your program. The code file testfile1.txt is correct, while the code file testfile2.txt is incorrect.

Useful code:

#include <fstream> string readFile() {      string tempString = "";      string filename;           cout << "Input file name: ";      cin >> filename;      ifstream inputFile(filename);           // Prompt user again if wrong filename received      while (!inputFile.good()) {           cout << "Wrong file name, input again please: ";           cin >> filename;           inputFile.open(filename);      }           // Append all lines from the file into a long string      while ((!inputFile.eof())) {           string str;           getline(inputFile, str);           tempString += str;      }           return tempString; }

///////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////

#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;
}

///////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////

#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;
}

///////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////

//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
/////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////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;
  
}

Please answer in c++

Answer 1

The code provided below, follows the exact algorithm given in the problem description, no extra thing have been added. Please note that the algorithm in the last gives "The code is correct" even when the number of opening symbol is equal to number of closing symbol, no matter what the order is. Also there was a confusion in the algorithm that after showing the errors, we had to end the program or had to go on till the end of file. The code just follows the algorithm and read the file till the last character, and if there is mismatch shows error and continue reading the next character. And in last prints the output. If the both testfiles will be generated according to the algorithm it will give the correct output.

for ex:

input file : " { ] "

the code will give a error of not equal but prints the code is correct (as for the algorithm says as the closing symbol comes, first pop the stack ( " { " ) and then match if it is corresponding to the closing symbol just read. so it will give the "not equal error", but as the stack is now empty after the stack, so the algorithm says the code is correct.

If you need the code which gives the code incorrect for this input file, the algorithm will be different, you can ask for that in comment section.

CODE(StackMain.cpp reamaining two files(StackArr.cpp & StackArr.h ) will be same):

// StackMain.cpp

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

using namespace std;

string readFile() {
     string tempString = "";
     string filename;
     cout << "Input file name: ";
     cin >> filename;
     ifstream inputFile(filename);
     // Prompt user again if wrong filename received

     while (!inputFile.good()) {
          cout << "Wrong file name, input again please: ";
          cin >> filename;
          inputFile.open(filename);
     }

    // Append all lines from the file into a long string
     while ((!inputFile.eof())) {
          string str;
          getline(inputFile, str);
          tempString += str;
     }
     return tempString;

}

void solve(string str){
    int n = str.length();       // CALCULATE THE LENGTH OF STRING IN THE FILE
    StackArr mystack(n);        // MADE THE EMPTY STACK OF SIZE == LENGTH OF STRING
    for(int i=0;i<n;i++){
        if (str[i]=='(' || str[i]=='{' || str[i]=='[')  // IF INPUT SYMBOL ENCOUNTERED JUST PUSH IT
            mystack.push(str[i]);
        else if(str[i]==')' || str[i]=='}'|| str[i]==']'){ // IF CLOSING SYMBOL
            if (mystack.isEmpty())                         // CHECK IF STACK IS EMPTY THEN SHOW ERROR
                cout<<"Error: Empty stack"<<endl;
            else{ 
                char ch = mystack.pop();                   // ELSE POP THE STACK
                if ((ch=='(' && str[i]==')') || (ch=='{' && str[i]=='}') || (ch=='[' && str[i]==']'))  // CHECK IF THE POPPED SYMBOL CORRESPONDS TO THE CLOSED SYMBOL READ IF IT IS CONTINUE
                    continue;
                else                                       // ELSE SHOW THE ERROR NOT EQUAL
                    cout<<"Error: Not equal"<<endl;

            }
        }

    }
    if (mystack.isEmpty())                             // AFTER READING ALL THE CHARACTERS, CHECK IF THE STACK IS EMPTY IF IT IS PRINT THE CODE IS CORRECT
        cout<<"The code is correct"<<endl;
    else
        cout<<"The code is incorrect"<<endl;           // ELSE PIRNT CODE IS INCORRECT


}

int main(){

    string str = readFile();
    cout<<"input file content: "<<str<<endl;
    solve(str);

    return 0;
}

OUTPUT(SAMPLE):

NOTE: In case of any query or doubt, or you want any modification in the code, you can mention that in comment section. HAPPY LEARNING!!