RPNcalc.c

/* Lab Assignment #4
 * Name: Brandon Jank
 * Due: February 19th, 2015
 *
 * A basic Reverse Polish Notation (RPN) Calculator that implements basic 
 *  math functions.
 *
 * Date Created: February 16th, 2015, 12:21 PM
 * Date Modified: February 18th, 2015, 6:40 PM
 */

#include <cstdlib> // strtod
#include <iostream>
#include <algorithm> // transform
#include <string> // find_first_not_of
#include <sstream>
#include <cmath> // sqrt
#include "stack.h"

using namespace std;

bool IsDouble(const string& str);
void PrintStack(Stack& stack);
void DoOperation(Stack& stack, string inputToken);

int main() {
    string input, inputToken;
    Stack stack;
    
    cout << endl << "RPN Calculator v0.1 by Brandon Jank" << endl;
    cout << "RPN (empty) > ";
    
    // get user input
    while (getline(cin, input)) {
        istringstream iss(input);
        // grab a token from the stream
        while (iss >> inputToken) {
            // convert to lower case
            transform(inputToken.begin(), inputToken.end(), 
                    inputToken.begin(), ::tolower);
            
            // decide what to do with the token
            if (IsDouble(inputToken)) {
                stack.Push(strtod(inputToken.c_str(), NULL));
            } else if (inputToken == "quit") {
                break;
            } else {
                DoOperation(stack, inputToken);
            }
        }
        // reprint the prompt
        cout << "RPN " << stack.Peek() << " > ";
        // break the outer loop too
        if (inputToken == "quit") 
            break;
    }
    return 0;
}

bool IsDouble(const string& str) {
    istringstream iss(str);
    double temp;
    iss >> noskipws >> temp;
    return (iss.eof() && !iss.fail()); 
}

// print the contents of the stack
void PrintStack(Stack& stack) {
    cout << "Stack contents: ";
    stack.Print();
    cout << endl;
}

// check and execute operation based on string input
void DoOperation(Stack& stack, string inputToken) {
    double operand1, operand2;
    if (inputToken == "+") {
        operand2 = stack.Pop();
        operand1 = stack.Pop();
        stack.Push(operand1 + operand2);
    } else if (inputToken == "-") {
        operand2 = stack.Pop();
        operand1 = stack.Pop();
        stack.Push(operand1 - operand2);
    } else if (inputToken == "*") {
        operand2 = stack.Pop();
        operand1 = stack.Pop();
        stack.Push(operand1 * operand2);
    } else if (inputToken == "/") {
        operand2 = stack.Pop();
        operand1 = stack.Pop();
        stack.Push(operand1 / operand2);
    } else if (inputToken == "sq") {
        operand1 = stack.Pop();
        stack.Push(operand1 * operand1);
    } else if (inputToken == "sqrt") {
        operand1 = stack.Pop();
        stack.Push(sqrt(operand1)); 
    } else if (inputToken == "dup") {
        operand1 = stack.Pop();
        stack.Push(operand1);
        stack.Push(operand1);
    } else if (inputToken == "swap") {
        operand2 = stack.Pop();
        operand1 = stack.Pop();
        stack.Push(operand2);
        stack.Push(operand1);
    } else if (inputToken == "ps") {
        PrintStack(stack);
    } else {
        // token is not a number or operation
        cerr << "ERROR: There was a problem with your input (" 
                << inputToken << ") and was ignored." << endl;
    }
}