Thread: I need help with RPN notation!!!

Hi,
I'm currently working on a program that converts infix notation to postfix notation, then calculates the postfix notation. I was successful in the conversion, but I can't get the calculation to work. Below is my code, can someone please help, I've been working on this for hours!

Any comments are appreciated. Thanks!

Code:

 
#include<iostream>

using namespace std;

/*-------------------- Stack class ----------------------*/
template<class T>
class Stack
{
  private:
      int size;
      int top;
      T *arrayptr;
  public:
      Stack(int=20);
      bool Push(T);
      T Pop();
      bool isfull();
      bool isempty();
};

template<class T>
Stack<T> :: Stack(int s)
{
  size = s > 0?s:20;
  top = -1;
  arrayptr = new T[size];
}

template<class T>
bool Stack<T> :: Push(T val)
{ 
  if(!isfull()){
      arrayptr[++top]=val;
      return true;}
  return false;
}

template<class T>
T Stack<T> :: Pop()
{
return arrayptr[top--];
}

template<class T>
bool Stack<T>::isfull()
{
  return top == size-1;

}

template<class T>
bool Stack<T>::isempty()
{
  return top == -1;
}

void eVal(char *str,Stack<char> s,int siz);

/*------------------------ main --------------------------*/

int main()
{
  Stack<char> s1;
  int sizestr;
  char string[20];

  cout << "Enter an infix expression: ";
  cin >> string;
  sizestr = strlen(string);
  
  cout << "The RPN Notation is: ";
  eVal(string,s1,sizestr);

  system("PAUSE");
  return EXIT_SUCCESS;
}

/*----------------------- eVal ---------------------------*/

void eVal(char *str,Stack<char> s,int siz)
{
  char pop1;
  char str2[20];

  for(int i = 0;i < siz;i++)
  {
      if(str[i] > '0' && str[i] <= '9')
	  {
          cout << str[i];
		  str2[i] = str[i];
	  }
      else if(str[i] == '*')
      {
          if(s.isempty())
          {
              s.Push(str[i]);
          }
          else
          {
              pop1 = s.Pop();
              if(pop1 == '(')
              {
                  s.Push(pop1);
                  s.Push(str[i]);
              }
              else if(pop1 == '*'|| pop1 =='/')
              {
				  str2[i] = pop1;
                  cout << pop1;
                  s.Push(str[i]);
              }
              else if(pop1 == '+' || pop1 == '-')
              {
                  s.Push(pop1);
                  s.Push(str[i]);
              }
          }
      }

      else if(str[i] == '/')
      {
          if(s.isempty())
          {
              s.Push(str[i]);
          }
          else
          {
              pop1 = s.Pop();
              if(pop1 == '(')
              {
                  s.Push(pop1);
                  s.Push(str[i]);
              }
              else if(pop1 == '*' || pop1 == '/')
              {
				  str2[i] = pop1;
                  cout << pop1;
                  s.Push(str[i]);
              }
              else if(pop1 == '+' || pop1 == '-')
              {
                  s.Push(pop1);
                  s.Push(str[i]);
              }
          }
      }

      else if(str[i] == '+')
      {
          if(s.isempty())
          {
              s.Push(str[i]);
          }
          else
          {
              pop1 = s.Pop();
              if(pop1 == '(')
              {
                  s.Push(pop1);
                  s.Push(str[i]);
              }
              else if(pop1 == '*' || pop1 == '/' || pop1 == '+' || pop1 == '-')
              {	
				  str2[i] = pop1;
                  cout << pop1;
                  s.Push(str[i]);
              }
          }
      }

      else if(str[i] == '-')
      {
          if(s.isempty())
          {
              s.Push(str[i]);
          }
          else
          {
              pop1 = s.Pop();
              if(pop1 == '(' )
              {
                  s.Push(pop1);
                  s.Push(str[i]);
              }
              else if(pop1 == '*' || pop1 == '/' || pop1 == '+' || pop1=='-')
              {
				  str2[i] = pop1;
                  cout << pop1;
                  s.Push(str[i]);
              }
          }
      }

      else if(str[i] == '(')
          s.Push(str[i]);
      else if(str[i] == ')')
      {
          pop1 = s.Pop();
          while(pop1 != '(')
          {
			  str2[i] = pop1;
              cout << pop1;
              pop1 = s.Pop();
          }
      }
  }

 while(!s.isempty())
 {
     cout << s.Pop();
 }
 cout << endl;
 int left, right;
 char type;
 int convert;

 for(i = 0;i < siz;i++)
 {
	 type = str2[i];
	 if (isdigit(type))
	 {
		 convert = str2[i] - '0';
		 i = convert;
		 s.Push(str2[i]);
	 }
	 else
	 {
		 switch(type)
		 {
			case '+':
				s.Push(s.Pop() + s.Pop());
				break;
			case '-':
				right = s.Pop();
				left = s.Pop();
				s.Push(left - right);
				break;
			case '*':
				s.Push(s.Pop() * s.Pop());
				break;
			case '/':
				right = s.Pop();
				left = s.Pop();
				s.Push(left / right);
				break;
			default: 
				throw domain_error("Undefined operator");
		 }
	 }
 }
cout << "Result: " << str2[0] << str2[1] << str2[2] << str2[3] << str2[4] <<  endl;
}

I understand that I need to break it up into smaller pieces, but I need some advice on how to transfer the RPN notation char's into a seperate array...