need help > the typical infix statements to postfix

I got stuck in this program and dont know how to start to phase 2, i finish phase 1 quite good bt i dont understand connection phase 1 and phase 2. so i hope some one can help me pls, thank you very much.....

phase 2:Expand Phase 1 to translate the typical infix statements to postfix. The postfix should be printed out and then calculated. For example: (3+5)*9? should output 3 5 + 9 * = 72.

and i finish my phase 1

header.h

Code:

---

#include <iostream>
#include <fstream>
#include <string>
using namespace std;

class Lexeme
{
private:
        string Lex;
        string type;

public:


        Lexeme();
        string getLex ();
        string gettype ();
        void setLex (string);
        void settype (string);
};

---

main.cpp

Code:

---

#include "TheHeader.h"
#include <stack>
void ReadFile();

int main ()
{
        ReadFile();
        return 0;
}
void ReadFile()
{
        char a;
        string str = "";
        Lexeme temp;
        stack <Lexeme> name;

        ifstream file ("sample.txt",ios::in);
        if(!file)
        {
                cout<<"Unable to open the file!!!" <<endl;
                exit(1);
        }
        file >> a;

        while (file)
        {
                if (a == '/' ||a == '*' ||a == '+' ||a == '-' ||a == ';' ||a == '^'||a == '='||a == '('||a == ')')
                {cout << a << " symbol" << endl ;
                str = a;
                temp.setLex(str);
                temp.settype("SYMBOL");
                name.push(temp);
                file >> a;
        }

        else {str = a;file >> a;
        while( a >= '0' && a <= '9' || a == '.')
        {

        str.append(1,a);
        file >> a;
        }
                temp.setLex(str);
                temp.settype("NUMBER");
                name.push(temp);
                cout << str << " number" <<endl ;
                str = "";
        }
        }

        file.close();
}

---

header.cpp

Code:

---

#include "TheHeader.h"



Lexeme::Lexeme()
{
Lex = "";
type ="";
}
        string Lexeme::getLex ()
        {
                return Lex;
        }
        string Lexeme::gettype ()
        {
                return type;
        }
        void Lexeme::setLex(string b)
        {
                Lex = b;
        }
        void Lexeme::settype (string c)
        {
                type = c;
        }

---

hope someone can guide me to right direction, i will spend all my time of this weekend to work on this problem only
thank you

ahh i just asked almost the same question, thought i could help give you some direction

Code:

---

toPostFix()
{
        Lexeme temp;
        List<Lexeme> your_List_Of_Infix;//use std::list or CList
        List<Lexeme> temp;//temporary

        Stack<Lexeme> theStack;

        //here i omited the parentheses "(" and ")", you may add it in the
        //switch statement after you get the normal equation withouth
        // the parentheses right first
        for(each item in your_List_Of_Infix)
        {
                switch(your_List_Of_Infix[i].getType)
                {
                case "NUMBER":
                        theStack.push(your_List_Of_Infix[i]);
                        break;
                case "SYMBOL":
                        while(!theStack.isEmpty() && your_List_Of_Infix[i] has highprecedence that topOfStack)
                        {
                                temp.AddTail(theStack.GetTop());
                                theStack.pop()
                        }
                        push(your_List_Of_Infix[i]);
                        break;
                };
        }

        //now get remaining items in stack
        while(!theStack.isEmpty())
        {
                temp.AddTail(theStack.GetTop());
                theStack.pop();
        }

        //now your "temp" list has the postfix expression,
        //all you need to do now is to iterate through the list to
        //and evaluate the expression to get the value,

        //pseudokod should be easy here, just use the same stack

        for (each item in temp list)
        {
                if type == NUMBER
                        push(the item)
                else if type == SYMBOL
                {
                        operand2 = top of stack;
                        pop stack;
                        operand1 = top of stack;
                        pop stack;

                        //operation here depand on the SYMBOL type
                        result = operand1 + operand2
                        push(result)
                }
        }

        //after the loop above, you'll get the result from the top of the stack.

}

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