Question

C++ Write a program that prompts for a file name and then reads the file to check for balanced curly braces, {; parentheses, (); and square brackets, []. Use a stack to store the most recent unmatched left symbol. The program should ignore any character that is not a parenthesis, curly brace, or square bracket. Note that proper nesting is required. For instance, [a(b]c) is invalid. Display the line number the error occurred on.

These are a few of the files that will be called, each named input1.cpp , input2.cpp and so on until input6.cpp -

input1.cpp

#include <iostream>

using namespace std;

void main (void)
{
   cout << "Hello World!" << endl;

}

input2.cpp

#include <iostream>

using namespace std;

void main (void)
   cout << "Hello World!" << endl;

}

Answer 1

----------------Stack.h-----------------

#ifndef MY_STACK

#define MY_STACK

#include<iostream>

#include<cstdlib>

#include<cstring>

#include<fstream>

using namespace std;

class Stack

{

    // declare stack array arr

    char *arr;

   

    // to store the index of the top most element

    int top;

   

    // to store the current capacity of arr

    int size;

   

    public:

       

        // constructor

        Stack();

       

        // constructor

        Stack(int);

       

        // destructor

        ~Stack();

       

        // function to check if the stack is empty

        bool isEmpty();

       

        // function to check if the stack is full

        bool isFull();

       

        // push element intot the stack

        void push(char);

       

        // return the top most element in the stack

        char peek();

       

        // pop element from stack

        void pop();

       

        // resize the array to double the original capacity

        void resize();

       

        // display contents of stack

        void view();

};

#endif

------------------Stack.cpp--------------------

#include "Stack.h"

// constructor

Stack::Stack()

{

    // declare an array of size 4

    arr = new char[4];

       

    // set initial capacity to 4

    size = 4;

       

    top = -1;

}

// constructor

Stack::Stack(int new_size)

{

    // declare an array of size new_size

    arr = new char[new_size];

       

    // set initial capacity to new_size

    this->size = new_size;

       

    top = -1;

}

// destructor

Stack::~Stack()

{

    delete arr;

    size = 0;

    top = -1;

}

// function to check if the stack is empty

bool Stack::isEmpty()

{

    if(top == -1)

        return true;

    return false;

}

// function to check if the stack is full

bool Stack::isFull()

{

    if(top == size - 1)

        return true;

    return false;

}

void Stack::push(char n)

{

    // if stack is full

    if(isFull())

        // resize the array to double the original capacity

        resize();

       

    arr[++top] = n;

}

// return the top most element in the stack

char Stack::peek()

{

   if(isEmpty())

        return -1;

       

    return arr[top];

}

// pop element from stack

void Stack::pop()

{

    // if stack is empty

    if(isEmpty())

        cout<<"The stack is alreasy empty";

   

    // remove the top most element of the stack

   top--;

}

// resize the array to double the original capacity

void Stack::resize()

{

    // create a new int array double the size of arr

    char *temp = new char[2 * size];

    int i;

   

    for( i = 0 ; i < size ; i++ )

        // cop contents of arr to temp

        temp[i] = arr[i];

   

    // set capacity to double the original capacity

    size *= 2;

   

    // set temp as the new stack array

    arr = temp;

}

// display contents of stack

void Stack::view()

{

    int i;

  

    for( i = 0 ; i <= top ; i++ )

        cout<<arr[i]<<" ";

       

    cout<<endl;

}

----------------------main.cpp--------------------

#include "Stack.cpp"

bool isInPair( char ch1 , char ch2 )

{

    return ( ch1 == '(' && ch2 == ')' ) || ( ch1 == '{' && ch2 == '}' ) || ( ch1 == '[' && ch2 == ']' );

}

bool isBalanced(string str)

{

    // create an object of type stack

    Stack ob;

   

    int i;

   

    for( i = 0 ; i < str.length() ; i++ )

    {

        // if the current bracket is opening bracket

        if(str[i] == '(' || str[i] == '{' || str[i] == '[')

            // push it into stack

            ob.push(str[i]);

        // if the current bracket is closing bracket

        else if( str[i] == ')' || str[i] == '}' || str[i] == ']' )

        {

            // check if stack is empty or not and the brackets on the top of stack and current character don't form a pair

            if(ob.isEmpty() || !isInPair( ob.peek() , str[i]) )

                return false;

            // check if stack is not empty or not and the brackets on the top of stack and current character form a pair

            else

                // remove top most element from stack

                ob.pop();

        }

    }

   

    // if stack is empty

    if( ob.isEmpty() )

        return true;

    else

        return false;

}

int main()

{

    cout<<"Enter file name : ";

    string fname, str;

   

    cin>>fname;

   

    // open file in read mode

    ifstream in(fname.c_str());

   

    // read complete line

    getline(in, str);

   

    if( isBalanced( str ) )

        cout<<"It is balanced.";

    else

        cout<<"it is not balanced.";

       

    return 0;

}

--------------------input.txt--------------------

{}(([][][[()(),|||'''"";;_-+= ]]))

Sample Output