Write a pseudocode algorithm for a calculator app that uses postfix notation. No

Question

Write a pseudocode algorithm for a calculator app that uses postfix notation. Normally ,we write arithmetic expressons like this: ((3 + 12) x ( 8 + 2)) x 7.

Explanation / Answer

stackADT.h #ifndef H_StackADT #define H_StackADT template class stackADT { public: virtual void initializeStack() = 0; //Method to initialize the stack to an empty state. //Postcondition: Stack is empty. virtual bool isEmptyStack() const = 0; //Function to determine whether the stack is empty. //Postcondition: Returns true if the stack is empty, // otherwise returns false. virtual bool isFullStack() const = 0; //Function to determine whether the stack is full. //Postcondition: Returns true if the stack is full, // otherwise returns false. virtual void push(const Type& newItem) = 0; //Function to add newItem to the stack. //Precondition: The stack exists and is not full. //Postcondition: The stack is changed and newItem is added // to the top of the stack. virtual Type top() const = 0; //Function to return the top element of the stack. //Precondition: The stack exists and is not empty. //Postcondition: If the stack is empty, the program // terminates; otherwise, the top element of the stack // is returned. virtual void pop() = 0; //Function to remove the top element of the stack. //Precondition: The stack exists and is not empty. //Postcondition: The stack is changed and the top element // is removed from the stack. }; #endif linkedstack.h #ifndef H_StackType #define H_StackType #include #include #include "stackADT.h" using namespace std; //Definition of the node template struct nodeType { Type info; nodeType *link; }; template class linkedStackType: public stackADT { public: const linkedStackType& operator= (const linkedStackType&); //Overload the assignment operator. bool isEmptyStack() const; //Function to determine whether the stack is empty. //Postcondition: Returns true if the stack is empty; // otherwise returns false. bool isFullStack() const; //Function to determine whether the stack is full. //Postcondition: Returns false. void initializeStack(); //Function to initialize the stack to an empty state. //Postcondition: The stack elements are removed; // stackTop = NULL; void push(const Type& newItem); //Function to add newItem to the stack. //Precondition: The stack exists and is not full. //Postcondition: The stack is changed and newItem is // added to the top of the stack. Type top() const; //Function to return the top element of the stack. //Precondition: The stack exists and is not empty. //Postcondition: If the stack is empty, the program // terminates; otherwise, the top element of // the stack is returned. void pop(); //Function to remove the top element of the stack. //Precondition: The stack exists and is not empty. //Postcondition: The stack is changed and the top // element is removed from the stack. linkedStackType(); //Default constructor //Postcondition: stackTop = NULL; linkedStackType(const linkedStackType& otherStack); //Copy constructor ~linkedStackType(); //Destructor //Postcondition: All the elements of the stack are removed. private: nodeType *stackTop; //pointer to the stack void copyStack(const linkedStackType& otherStack); //Function to make a copy of otherStack. //Postcondition: A copy of otherStack is created and // assigned to this stack. }; //Default constructor template linkedStackType::linkedStackType() { stackTop = NULL; } template bool linkedStackType::isEmptyStack() const { return(stackTop == NULL); } //end isEmptyStack template bool linkedStackType:: isFullStack() const { return false; } //end isFullStack template void linkedStackType:: initializeStack() { nodeType *temp; //pointer to delete the node while (stackTop != NULL) //while there are elements in //the stack { temp = stackTop; //set temp to point to the //current node stackTop = stackTop->link; //advance stackTop to the //next node delete temp; //deallocate memory occupied by temp } } //end initializeStack template void linkedStackType::push(const Type& newElement) { nodeType *newNode; //pointer to create the new node newNode = new nodeType; //create the node newNode->info = newElement; //store newElement in the node newNode->link = stackTop; //insert newNode before stackTop stackTop = newNode; //set stackTop to point to the //top node } //end push template Type linkedStackType::top() const { assert(stackTop != NULL); //if stack is empty, //terminate the program return stackTop->info; //return the top element }//end top template void linkedStackType::pop() { nodeType *temp; //pointer to deallocate memory if (stackTop != NULL) { temp = stackTop; //set temp to point to the top node stackTop = stackTop->link; //advance stackTop to the //next node delete temp; //delete the top node } else cout link = NULL; //set the link field of the //node to NULL last = stackTop; //set last to point to the node current = current->link; //set current to point to //the next node //copy the remaining stack while (current != NULL) { newNode = new nodeType; newNode->info = current->info; newNode->link = NULL; last->link = newNode; last = newNode; current = current->link; }//end while }//end else } //end copyStack //copy constructor template linkedStackType::linkedStackType( const linkedStackType& otherStack) { stackTop = NULL; copyStack(otherStack); }//end copy constructor //destructor template linkedStackType::~linkedStackType() { initializeStack(); }//end destructor //overloading the assignment operator template const linkedStackType& linkedStackType::operator= (const linkedStackType& otherStack) { if (this != &otherStack) //avoid self-copy copyStack(otherStack); return *this; }//end operator= #endif #include #include #include "stackADT.h" #include "linkedStack.h" #include "string.h" using namespace std; //*********************************************************************************** // //int j=0; //char myOperator; void InToPost(char [] , char []); int priority(char ); //*********************************************************************************** //main() function int main() { // ifstream myFile; char myInfixString[30]; char myPostfixString[30]; // myFile.open("lab6.dat"); while(myFile.getline(myInfixString,29)) { cout

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