# Designing an RPN expression calculator in C homework help

In this assignment, one should enter an expression consisting of a series of tokens and evaluate it step by step. The program created by our C homework helpers has tokens that can be used as either an integer value or a mathematical operation (+,-,*,/,%), << to display the stack. ^ displays the top of the stack and removes it, and \ exits the program. Any other input is ignored. It needs to use a template to implement the stack.

## RPN Expression Calculator Simulation

```#pragma once #include #include"StackADT.h" template class LinkedStack : public StackADT { // inner struct represnets the linked list node structure struct Node{ T data; Node* next; }; Node* head; // head of the linkedlist Node* tail; // tail of the linkedlist int size; // number of elements in the list void printHelper(Node * node); // recursion function to help print stack public: LinkedStack(); void push(const T& data); // push data into stack void pop(); // pop data from the stack T top(); // peek the top of the stack bool isEmpty(); // check if the stack is already empty int getSize(); // returns the size of the stack void print(); // prints all the elements in the stack bool isFull(); ~LinkedStack(); // delete all elements in the stack to not cause a memory leak }; template LinkedStack::LinkedStack() { head = nullptr; size = 0; } template void LinkedStack::push(const T& data){ size++; if (head == nullptr){ // if the list is already empty head = new Node(); head->data = data; head->next = nullptr; tail = head; return; } Node* cur = head; while (cur->next != nullptr) { // iterate to the last element in the list cur = cur->next; } // append data to the end of the list cur->next = new Node(); cur->next->data = data; cur->next->next = nullptr; tail = cur->next; return; } template void LinkedStack::pop(){ assert(size > 0); // pop function is to delete last node in the list size--; if (head == tail){ // one element list => delete the head only delete head; head = tail = nullptr; return; } Node *cur = head; while (cur->next != tail){ // search for the last element in the list cur = cur->next; } // delete that element delete cur->next; cur->next = nullptr; tail = cur; return; } template T LinkedStack::top(){ assert(size > 0); return tail->data; } template int LinkedStack::getSize(){ return size; } template bool LinkedStack::isEmpty(){ return size == 0; } template LinkedStack::~LinkedStack(){ if (size == 0){ return; } // clears the memory so no memory leaks can happen if (head->next == nullptr){ // one element list => just delete the head. delete head; return; } Node * cur = head; Node* temp; // iterate over the list and delete element by element while (cur->next != nullptr){ temp = cur->next->next; delete cur->next; cur = temp; } delete cur; delete head; } template void LinkedStack::print(){ if (head == nullptr){ // empty list print cout << "<>"<"< void LinkedStack::printHelper(Node * node){ if (node->next == nullptr){ cout << node->data; return; } printHelper(node->next); cout << ", " << node->data; } template bool LinkedStack::isFull(){ return !isEmpty(); } StackADT.h #ifndef STACK_ADT #define STACK_ADT template class StackADT{ //Function to add a new item to the stack //Precondition: Stack exists and is not full //Post Condition: Stack is changed and the new item //is added to the top of the stack virtual void push(const T&) = 0; //Function to remove the top element from the stack //Precondition: Stack exists and is not empty //Post Condition: Stack is changed and the top element is removed from the stack virtual void pop() = 0; //Function to return the top element from the stack //Precondition: Stack exists and is not empty //Post Condition: If the stack is empty, the program returns, otherwise, //the top element of the stack is returned virtual T top() = 0; //Function to determine whether the stack is empty //Post Condition: Returns 1 of the stack is empty //otherwise returns 0 virtual bool isEmpty() = 0; //Function to determine whether the stack is full //Post Condition: Returns 1 of the stack is full //otherwise returns 0 virtual bool isFull() = 0; }; #endif Source.cpp #define _CRT_SECURE_NO_WARNINGS #include"LinkedStack.h" #include #include using namespace std; // Returns true if all the chars in the token is zeros. this function used to differentiate between // the atoi result zeros for bad parsing or actual zero. bool isZero(char* tok){ for (int i = 0; i < strlen(tok); i++){ if (tok[i] != '0'){ return false; } } return true; } // Returns true if all the chats in the tokens are numbers. this function is used to differntitate between // total correct int num and not completly correct ones(as atoi function returs 15 for both '15' and '15.625') bool totalNumber(char*tok){ for (int i = 0; i < strlen(tok); i++){ if (tok[i] < '0' || tok[i] > '9'){ return false; } } return true; } int main(){ LinkedStack stack; string exp; // total expression from user char tok; // token taken from the expression int num,num2; // numbers holders for operations bool exit = false; int res; // final result tracker cout << "Enter the expression: "; getline(cin,exp); while (!exit){ // these next three lines used to extract the next token from the expression sscanf(exp.c_str(), "%s ", &tok); if (strlen(tok) + 1 < exp.size()) exp = exp.substr(strlen(tok)+1); // work with token "tok" num = atoi(tok); if (num != 0){ // check if number is totally correct integer number if (!totalNumber(tok)){ cout << "invalid input" << endl; continue; } stack.push(num); } else if (isZero(tok)){ // to differntiate between the zero from atoi when bad parsing happen // or when an actual zero is passed stack.push(0); } else if (strcmp(tok, "<<") == 0){ stack.print(); } else if (strcmp(tok, "^") == 0){ cout<```