RPN.rar_RPN calculator

#include <iostream> #include <cstdio> #include <cctype> #include <cstdlib> #include "stack.h" using namespace std; int main() { //variables declaration Stack S; int num; int op1,op2; int c; cout <<"Welcome to Reverse Polish Notation calculator (RPN)\n"; cout << "-------------------------------------------\n"; cout << "please enter the number and the math symbol using the following format\n"; cout << " X_Y_+ (or-, *, /)\n"; cout << " e\n\n"; cout << "Warn: each input is seperated by a 'space'\n"; cout << "-------------------------------------------\n"; cout << "Direction for commands:"; cout << "press 'e' to print out the result\n"; cout << " press 'd' to reset the stack\n"; cout << " press 'q' to print out the result and exit\n"; while((c=getchar()) != EOF) { if(isdigit(c))//ask user to input the stack one by one { ungetc(c, stdin); scanf("%d", &num); S.push(num); } else { switch(c)//different cases of operations { case '+': S.push(S.pop() + S.pop()); break; case '-': op2 = S.pop(); op1 = S.pop(); S.push(op1 - op2); break; case '*': S.push(S.pop() * S.pop()); break; case '/': op2 = S.pop(); op1 = S.pop(); if(op2 == 0) { cerr << "Error: divided by zero!" << endl; exit(1); } S.push(op1 / op2); break; case 'e'://different cases for execution cout << "result: " << S.pop() << endl; break; case 'd': while(!S.empty()) S.pop(); break; case 'q': cout << "result: " << S.pop() << endl; return 0; break; } } } return 0; }