Question

JAVA, please

You must write a robust program meaning that your program should not crash with any given data. Data validation must be done any time that user enters an input. Write a program that 1. Gets an infix expression form the user and evaluate the expression using stack ADT a. Finds the postfix equivalent of the given infix expression b. Evaluate the created postfix expression. c. Note: your program should not crash when you enter an invalid expression such as: 2 + 4 * (6 -3 2. Implementation: a. Create an interface called Stack with the following methods. All the actual/formal parameters must be of type Object i. size(): returns the size of the stack ii. isEmpty() returns true/false iii. pop returns the object that is at the top of the stack iv. push(Object o) : pushes the object to the top of the stack v. pee(): looks at the object at the top and returns a copy of the object without popping it b. Create another class that implements the Stack interface. This class must have i. an instance variable of type ArrayList ii. implements all the methods from the stack interface iii. add equals method that compares two stacks iv. add a toString method. v. Add a method copy that returns a copy of the stack. c. Implement the driver class with the following methods i. infixToPostfix(String s): This method receives an infix expression and then creates its postfix and returns it. go to the website http://docs.oracle.com/javase/6/docs/api/java/util/StringTokenizer.html and read about the class called StringTokenizer. You need to use this class to tokenize the expression that you receive. In the expression 2 + 3, the tokens are 2, 3, +. If there are any spaces in the expression they must be ignored. Here is the algorithm to convert infix to postfix:  Initialize the stack with the dummy operator #.  Repeat until no more tokens. • Get the next token.  If the next token is an operand, enqueue the operand to the postfix String. Declare a String called postfix, every time you read an operand concatenate that to the postfix string.  If the next token is a (, push it in the stack.  If the next token is a ), pop and enqueue operators to the postfix string until a ( is on the top of the stack. Pop ( out of the stack.  If the next token is an operator, pop and enqueue operators to the postfix until the top of the stack has a lower precedence. Push the current operator into the stack. • If more tokens go to the beginning, If no more tokens, pop and enqueue operators until the dummy oprerator # is on the top of the stack. Pop # out of the stack. • Return the postfix String.  Note that # and (has a precedence lower than other operators. ii. Write a method called: postFixEvaluater(String post) . Use the following algorithm to evaluate a postfix expression. Repeat until no more tokens Get the next token: 1. If the next token is an operand, push it into the stack. 2. If the next token is an operator pop two operands from the stack, do the operation, and push the result back to the stack. After you are done reading all the tokens and doing the operations, the final result is the only thing on the stack when done. (If there’s more than one thing in the stack, there is an error in the expression.) Here is a sample output: Enter your infix expression: 3+7*6/3-8*2 postFix = 3 7 6 * 3 / + 8 2 * - 3 7 6 * 3 / + 8 2 * - = 1 Do you have another expression: yes Enter your infix expression:(7+9)*(6+3*5/3) postFix = 7 9 + 6 3 5 * 3 / + * 7 9 + 6 3 5 * 3 / + * = 176 Do you have another expression :yes Enter your infix expression:3+8*5-3+25/5 postFix = 3 8 5 * + 3 - 25 5 / + 3 8 5 * + 3 - 25 5 / + = 45 Do you have another expression :yes Enter your infix expression :(7+9)*(6+3*5/3 Invalid expression Do you have another expression :no Good Bye

Answer 1

`Hey,

Note: Brother in case of any queries, just comment in box I would be very happy to assist all your queries

Stack.h

#ifndef STACK_H

#define STACK_H

#include <iostream>

template <class T>

class StackNode

{

private:

T value;

StackNode<T> *next;

public:

StackNode(T newItem, StackNode<T> *newNext)

{

value = newItem;

next = newNext;

}

StackNode<T> *getNext()

{

return next;

}

T getData()

{

return value;

}

};

// Stack class

template <class T>

class Stack

{

private:

StackNode<T> *top;

public:

Stack();

// Push

void push(T newItem);

// Peek

T peek();

// Pop

T pop();

// isEmpty

bool isEmpty();

// clear

void clear();

// display stack contents

void display();

};

#endif

Stack.cpp

#include "Stack.h"

// Note: if you get an error about nullptr, try using -std=c++0x commandline switch

// or whatever compiler switch forces C++11 standard compiling (-std=c++0x is for g++).

// Stack class

template <class T>

Stack<T>::Stack()

{

top = nullptr;

}

// Push

template <class T>

void Stack<T>::push(T newItem)

{

StackNode<T> *n = new StackNode<T>(newItem, top);

top = n;

}

// Peek

template <class T>

T Stack<T>::peek()

{

return top->getData();

}

// Pop

template <class T>

T Stack<T>::pop()

{

T data;

StackNode<T> *ptr;

if (top == NULL)

return -1;

ptr = top;

top = top->getNext();

data = ptr->getData();

delete ptr;

return data;

}

// isEmpty

template <class T>

bool Stack<T>::isEmpty()

{

return top == nullptr;

}

// clear

template <class T>

void Stack<T>::clear()

{

//top = nullptr;

StackNode<T> *ptr = top, *prev = NULL;

top = nullptr;

while (ptr != NULL)

{

prev = ptr;

ptr = ptr->getNext();

delete prev;

}

}

// display stack contents

template <class T>

void Stack<T>::display()

{

StackNode<T> *node = top;

while (node != NULL)

{

std::cout << node->getData();

node = node->getNext();

}

}

main.cpp

#include <iostream>

#include <cstdlib>

#include <string>

#include <cstring>

#include <fstream>

#include <cmath>

#define OPERATORS 8

using namespace std;

#include "Stack.cpp"

char precedence[OPERATORS][2] = {{'(', 0}, {'+', 1}, {'-', 1}, {'*', 2}, {'/', 2}, {'%', 2}, {'^', 3}, {')', 4}};

/* get the index of the operator in precedence array */

int getIndex(int data)

{

int i;

for (i = 0; i < OPERATORS; i++)

{

if (data == precedence[i][0])

return i;

}

return -1;

}

string convertToPostfix(string infix)

{

Stack<char> *expr = new Stack<char>();

string postfix = "";

int i;

char data;

int index1, index2;

for (i = 0; i < (int)infix.length(); i++)

{

if (infix[i] == ' ')

continue;

/* given input is operator or not */

if ((tolower(infix[i]) >= 'a' && tolower(infix[i] <= 'z')) || (infix[i] >= '0' && infix[i] <= '9'))

{

postfix += infix[i];

if (infix[i + 1] <= '0' || infix[i + 1] >= '9' )

postfix += ' ';

}

else if (infix[i] == ')')

{

data = expr->pop();

while (data != '(' && data != -1)

{

postfix += data;

postfix += ' ';

data = expr->pop();

}

}

else if (infix[i] == '(')

{

expr->push(infix[i]);

}

else

{

data = expr->pop();

if (data == -1)

{

expr->push(infix[i]);

continue;

}

else if (data == '(')

{

expr->push(data);

expr->push(infix[i]);

continue;

}

index1 = getIndex(data);

index2 = getIndex(infix[i]);

while (precedence[index1][1] >= precedence[index2][1])

{

postfix += data;

postfix += ' ';

data = expr->pop();

if (data == -1)

{

expr->push(infix[i]);

break;

}

else if (data == '(')

{

expr->push(data);

expr->push(infix[i]);

data = -1;

break;

}

index1 = getIndex(data);

}

if (data != -1)

{

expr->push(data);

expr->push(infix[i]);

}

}

}

while (1)

{

if ((data = expr->pop()) == -1)

break;

postfix += data;

postfix += ' ';

}

return postfix;

}

int EvalPostfix(string str)

{

Stack<int> *expr = new Stack<int>();

int i,data = -1, operand1, operand2, result;

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

{

if (isdigit(str[i]))

{

data = (data == -1) ? 0 : data;

data = (data * 10) + (str[i] - 48);

continue;

}

if (data != -1)

{

expr->push(data);

}

if (str[i] == '+' || str[i] == '-' || str[i] == '*' || str[i] == '/' || str[i] == '^')

{

operand2 = expr->pop();

operand1 = expr->pop();

if (operand1 == -1 || operand2 == -1)

break;

switch (str[i])

{

case '+':

result = operand1 + operand2;

expr->push(result);

break;

case '-':

result = operand1 - operand2;

expr->push(result);

break;

case '*':

result = operand1 * operand2;

expr->push(result);

break;

case '/':

result = operand1 / operand2;

expr->push(result);

break;

case '^':

result = pow(operand1, operand2);

expr->push(result);

break;

}

}

data = -1;

}

if (!expr->isEmpty())

return expr->peek();

else{

cout<<"Invalid expression"<<endl;

exit(1);

}

}

int main()

{

string output, str, another;

do{

cout << "\nEnter your infix expression: ";

getline(cin, str);

output = convertToPostfix(str);

cout << "postfix: " << output << endl;

cout<<output<<" = "<<EvalPostfix(output)<<endl;

cout<<"Do you have another expression: ";

cin>>another;

cin.ignore();

}while(another=="yes");

cout<<"Good Bye"<<endl;

return 0;

}

Kindly revert for any queries

Thanks.