Prefix to Postfix

*/

#include <cstdlib>
#include <iostream>
#include <string>

#include<map>
using namespace std;

/*
 *
 */


class post {
private:
    string stack;

    string prefix;
    map<char, int> op;

public:
    string postfix;

    post(string pre) : prefix(pre) {
        stack.clear();
        //Operator value table
        op['-'] = 1;
        op['+'] = 2;
        op['/'] = 3;
        op['*'] = 4;
        op['^'] = 5;
        op[')'] = -1;
        op['('] = -1;
    }

    void scan() {
        for (int i = 0; i < prefix.length(); i++) {
            if (isdigit(prefix[i])) {
                postfix += prefix[i];
            } else if(prefix[i] != ' ') {
                checkStack(prefix[i]);
            }
        }
        for (int i = stack.length(); i >= 0; i--) {
            if (op[stack[i]] != -1)
                postfix += stack[i];
        }

    }

    void checkStack(char sym) {
        int i = stack.length() - 1;
        int newsym = op[sym];
        cout << stack << endl;

        if (stack.empty()) {
            stack += sym;
            return;
        } else {
            if (newsym > op[stack[i]]) {
                stack += sym; //push
                return;
            } else {
                while (newsym <= op[stack[i]]) {
                    if (op[stack[i]] != -1)
                        postfix += stack[i]; //pop in to the postfix expression
                    stack.erase(stack.end() - 1); //pop out the stack
                    i--;
                    if (stack.empty())
                        break;
                }
                stack += sym; //push
            }

        }

    }

};

int main(int argc, char** argv) {

    string prefix = "(5+3)*12/3";
    post postfix(prefix);
    postfix.scan();
    cout << postfix.postfix;


    return 0;
}