Polish notation C++ code

[hdn]

I saw many people have problem with Polish notation code, so I decide to share my "Polish notation Code" (write in C++). Hope this would help someone. This is just an example as a reference, don't take it as a complete program!!!

Math.txt -- Put something like: 5+6-7*3+5*6-7*9-3
MathOutput.txt -- Leave empty and your computer will fill with: 5673*-56*79*-3-++ (if you use Output function in void main())

here is PolishNotation.cpp

 //#include "stdafx.h"
#include "iostream"
#include "fstream"
#include "string"
#include "Stack.h"
#include "stack"
using namespace std;

#define FI "Math.txt"
#define FO "MathOutput.txt"

ifstream fi;
ofstream fo;

void Input(char A[])
{
    fi.open(FI);
    fi>>A;
    fi.close();
}
void Output(char B[])
{
    fo.open(FO);
    fo<<B;
    fo.close();
}

int calculation(int oper1, int oper2, char chr)
{
    switch (chr)
    {
        case '+':
            return oper1 + oper2;
        case '-':
            return oper1 - oper2;
        case '*':
            return oper1 * oper2;
        case '/':
            return oper1 / oper2;
        default: cerr << "undefined behavor\n";
                         break;
    }
}
void Trans(char A[],char B[])
{
    int i=0,j=0;
    Stack<char> S;
    while(A[i] != 0)
    {
        if(A[i] >=48 && A[i] <=57)
        {
            B[j] = A[i];
            j++;
        }
        if(A[i] == '*' || A[i] == '/')
        {
            S.push(A[i]);
        }
        if(A[i] == '+' || A[i] == '-')
        {
            if(S.IsEmpty())
                S.push(A[i]);
            else
                if(S.top() == '*' || S.top() == '/' || S.top() == '-')
                {
                    while(S.top() == '*' || S.top() == '/' || S.top() == '-')
                    {
                    B[j] = S.pop();
                    j++;                   
                    }
                    S.push(A[i]);
                }
                else
                {
                    S.push(A[i]);
                }
        }
        i++;
    }
    while(!S.IsEmpty())
    {
        B[j] = S.pop();
        j++;
    }
}
int ReadMath(char A[])
{
    int i=0,n1,n2;
    Stack<int> Num;
    while(A[i] != 0)
    {
        if(A[i] >=48 && A[i] <=57)
        {
            Num.push(A[i]-48);
        }
        if(A[i] == '*' || A[i] == '/' || A[i] == '+' || A[i] == '-')
        {
            n2=Num.pop();
            n1=Num.pop();
            Num.push( calculation(n1,n2,A[i]));
        }
        i++;
    }
    return Num.top();
}

void main()
{
    char M[30]={NULL};
    char N[30]={NULL};
    Input(M);
   
    Trans(M,N);
    //Output(N);
    cout<<N<<endl;
    cout<<M<<"= "<<ReadMath(N)<<endl;
}

here is Stack.h (you can write this yourself)

#include "iostream"
#include "fstream"

using namespace std;

template<class T>
struct Node
{
    T Data;
    Node* pNext;
};
template<class T>
class Stack
{
protected:
    Node<T> *pHead;
    Node<T> *pTail;
    Node<T>* GetNODE(T x);
    void AddTail(Node<T>* x);
    void AddFirst(Node<T>* x);
    T RemoveHead();
public:
    Stack();
    bool IsEmpty();
    void push(T x);
    T pop();
    T top();
    ~Stack();
};

template<class T>
Stack<T>::Stack()
{
    this->pHead = NULL;
    this->pTail = NULL;
}

template<class T>
bool Stack<T>::IsEmpty()
{
    if(this->pHead == NULL)
        return true;
    else
        return false;
}

template<class T>
Node<T>* Stack<T>::GetNODE(T x)
{
    Node<T> *p;
    p = new Node<T>;
    if(p==NULL)
    {
        cout<<"\nMemory overload\n";
        return NULL;
    }
    p->Data = x;
    p->pNext = NULL;
    return p;
}
template<class T>
void Stack<T>::AddTail(Node<T>* x)
{
    if(this->pHead == NULL)
    {
        this->pHead = x;
        this->pTail = this->pHead;
    }
    else
    {
        this->pTail->pNext = x;
        this->pTail = x;
    }
}
template<class T>
void Stack<T>::AddFirst(Node<T>* x)
{
    if(this->pHead == NULL)
    {
        this->pHead = x;
        this->pTail = this->pHead;
    }
    else
    {
        x->pNext = this->pHead;
        this->pHead = x;
    }
}

template<class T>
void Stack<T>::push(T x)
{
    Stack<T>::AddFirst(GetNODE(x));
}

template<class T>
T Stack<T>::RemoveHead()
{
    Node<T>* p;
    T x;
    if(this->pHead != NULL)
    {
        p = this->pHead;
        x = p->Data;
        this->pHead = this->pHead->pNext;
        delete p;
        if(this->pHead == NULL)
            this->pTail = NULL;
        return x;
    }
    return NULL;
}

template<class T>
T Stack<T>::pop()
{
    T x;
    if(Stack<T>::IsEmpty())
        return NULL;
    x = Stack<T>::RemoveHead();
    return x;
}

template<class T>
T Stack<T>::top()
{
    if(Stack<T>::IsEmpty())
        return NULL;
    return this->pHead->Data;
}

template<class T>
Stack<T>::~Stack()
{
    Node<T> *p;
    while(this->pHead != NULL)
    {
        p = this->pHead;
        this->pHead = this->pHead->pNext;
        delete p;
    }
    this->pTail = NULL;
    //cout<<endl<<"            \1 \3 \2 HAVE A NICE DAY \1 \3 \2"<<endl;
}