Programming Assignment #6- Match Brackets using a Stack: Given a text file, your

Question

Programming Assignment #6- Match Brackets using a Stack:

Given a text file, your program will determine if all the parentheses, braces, and square brackets match, and are nested appropriately. Your program should work for mathematical formulas and most computer programs.

Your program should read in the characters from the file, but ignore all characters except for the following: { } ( ) [ ]

Your program should use the IntStack declaration (IntStack.h), which will be available from Tracs).

The general algorithm is to use a stack to store the opening unmatched brackets. When a closing bracket is encountered, check it against the one on top of the stack-- make sure it matches, and pop it off. When you are finished there should be no unmatched brackets left on the stack.

Input/Output:

Your driver program must prompt the user to enter a filename. It should then try to open the file and then check it to ensure the brackets all match appropriately. If they all match, the program should output a message saying so. If not, the program should output an appropriate error message (there are three possible error messages corresponding to three types of errors shown as follows).

There are three types of errors that can happen (and with any kind of bracket):

missing } : if you reach the end of the file, and there is an opening { that was never matched, like: int main () { x[size]=10;

expected } but found ) : this is a wrong closing bracket, like: {x[i]=10;)...

unmatched } : this occurs if there is a closing bracket but not an opening bracket (not even one of the wrong kind), like: int main () { x[i]=10; } }...

NOTES:

This program must be done in a Linux or Unix environment, using a command line

compiler like g++. Do not use codeblocks, eclipse, or Xcode to compile.

As soon as your driver encounters an error, your program should stop and print out

the appropriate error message. Do NOT try to keep going and find more errors!

The stack is an int stack but you will probably want to put characters on the stack. You can push a character directly on the int stack (it will automatically be converted to an int). When you pop I recommend popping into a char variable first (this will automatically convert the int back into a character).

It might be easier to store the expected closing character on the stack when an opening bracket is encountered. This simplifies the matching when a closing bracket is encountered.

Beware of stack underflow! Do NOT try to pop an empty stack! If you get an error message like this when you run your program: Assertion failed: (!isEmpty())
then you are popping an empty stack: your program should prevent this and output its own appropriate error message instead.

Follow the style guidelines from the Tracs.

Logistics:

For this assignment you need to submit two files: IntStack.cpp and your driver file. Please zip these into one file, assign6_xxxxxx.zip (where xxxxx is your NetID). Then submit the zip file

Submit an electronic copy using the Assignments tool in TRACS before the deadline.

Here is the given file:

Explanation / Answer

CODE:- #include #include class Node { private: int value; Node* prev; public: int returnValue() { return value; } Node* returnPtr() { return prev; } /* constructors and destructors */ Node(int val, Node* ptrToLast) { value = val; prev = ptrToLast; } }; class Stack { private: Node* top; int size; public: Stack() { size = 0; top = NULL; } //added this after told the need for a destructor; not sure if it works ~Stack() { while (top != NULL) { Node* tempPtr = top.returnPtr(); delete top; top = tempPtr; } } Node* returnTopPtr() { return top; } void push(int); int pop(); int peek(); //bonus; figured it might be worth knowing how many //nodes are in a given stack int returnSize(); }; int Stack::returnSize() { return size; } void Stack::push(int value) { ++size; Node* tempPtr = top; top = new Node(value, tempPtr); } int Stack::peek() { return top->returnValue(); } int Stack::pop() { const std::string throwStr = "You are trying to access/delete a node that doesn't exist. Seriously. "; if (size == 0) { throw(throwStr); } --size; Node* tempPtr = top->returnPtr(); int tempVal = top->returnValue(); delete top; top = tempPtr; return tempVal; }

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