Infix to Postfix code conversion - c++

Question

I have problem to convert infix to postfix this is my code it takes the characterinfix input but does not show any postfix output Please tell me whats the problem.I have been trying to solve it but i found no problem in it i will be thanks full you if someone find the problem.And the other thing is how may i add {} and [] this brackets too ?
#include <iostream>
#include<string.h>
using namespace std;
template <class T>
class Node
{
public:
T info;
Node *ptrnext;
Node *ptrprevious;
Node()
{
info = 0;
ptrnext = 0;
ptrprevious = 0;
}
Node(T e, Node *n, Node *p)
{
info = e;
ptrnext = n;
ptrprevious = p;
}
};
template <class T>
class DLinkedList
{
private:
Node<T> *head;
Node<T> *tail;
public:
DLinkedList()
{
head = 0;
tail = 0;
}
bool isEmpty();
void addToHead(T e);
void addToTail(T e);
void deleteFromHead();
void deleteFromTail();
void display();
T getHead();
int numofNodes();
~DLinkedList(){
if(!isEmpty())
{
while(head!=0){
if(head==tail)
{
delete head;
head=0;
tail=0;
}
else{
Node<T> *ptrtemp=head;
head=head->ptrnext;
head->ptrprevious=NULL;
delete ptrtemp;
}
}
}
}
};
template <class T>
bool DLinkedList<T>::isEmpty()
{
if (head == 0)
{
return true;
}
else
{
return false;
}
}
template <class T>
void DLinkedList<T>::addToHead(T e)
{
Node<T> *ptrnode = new Node<T>(e,0,0);
if(isEmpty())
{
head = ptrnode;
tail = ptrnode;
}
else
{
ptrnode->ptrnext = head;
head->ptrprevious = ptrnode;
ptrnode->ptrprevious = 0;
head = ptrnode;
}
}
template <class T>
void DLinkedList<T>::addToTail(T e)
{
Node<T> *ptrnode = new Node<T>(e,0,0);
if(isEmpty())
{
head = ptrnode;
tail = ptrnode;
}
else
{
tail->ptrnext = ptrnode;
ptrnode->ptrprevious = tail;
ptrnode->ptrnext = 0;
tail = ptrnode;
}
}
template <class T>
void DLinkedList<T>::deleteFromHead()
{
if(!isEmpty())
{
if(head == tail)
{
delete head;
head = 0;
tail = 0;
}
else
{
Node<T> *ptrtemp = head;
head = head->ptrnext;
head->ptrprevious = 0;
delete ptrtemp;
}
}
}
template <class T>
void DLinkedList<T>::deleteFromTail()
{
if(!isEmpty())
{
if(head == tail)
{
delete tail;
head = 0;
tail = 0;
}
else
{
Node<T> *ptrtemp = tail;
tail = tail->ptrprevious;
tail->ptrnext = 0;
delete ptrtemp;
}
}
}
template <class T>
void DLinkedList<T>::display()
{
if(!isEmpty())
{
Node<T> *ptrtemp = head;
while(ptrtemp->ptrnext != 0)
{
cout<<ptrtemp->info;
ptrtemp = ptrtemp->ptrnext;
}
cout<<ptrtemp->info<<endl;
}
}
template <class T>
T DLinkedList<T>::getHead()
{
if(isEmpty())
{
return 0;
}
else
{
return head->info;
}
}
template <class T>
int DLinkedList<T>::numofNodes()
{
if(isEmpty())
{
return 0;
}
else
{
int count = 0;
Node<T> *ptrtemp = head;
while(ptrtemp->ptrnext != 0)
{
count++;
ptrtemp = ptrtemp->ptrnext;
}
count++;
return count;
}
}
template <class T>
class Stack:public DLinkedList<T>
{
private:
int maxStackSize;
public:
Stack()
{
maxStackSize = 10;
}
bool isEmpty();
bool isFull();
void Push(T e);
T Pop();
void display();
T topvalue();
};
template <class T>
bool Stack<T>::isEmpty()
{
bool r= DLinkedList<T>::isEmpty();
return r;
}
template <class T>
bool Stack<T>::isFull()
{
int totalNodes = DLinkedList<T>::numofNodes();
if(totalNodes == maxStackSize)
{
return true;
}
else
{
return false;
}
}
template <class T>
void Stack<T>::Push(T e)
{
if( isFull() )
{
cout<<"Stack Full "<<endl;
}
else
{
DLinkedList<T>::addToHead(e);
}
}
template <class T>
T Stack<T>::Pop()
{
if(isEmpty())
{
return 0;
}
else
{
T n = DLinkedList<T>::getHead();
DLinkedList<T>::deleteFromHead();
return n;
}
}
template <class T>
void Stack<T>::display()
{
if( isEmpty() )
{
cout<<"Stack Empty!!"<<endl;
}
else
{
DLinkedList<T>::display();
}
}
template<class T>
T Stack<T>::topvalue()
{
T temp;
temp=DLinkedList<T>::getHead();
return temp;
}
int main()
{
Stack<char> obj;
char input[20];
cout<<"Enter Values \n";
cin>>input;
int size= strlen(input);
for(int i=0; i <size ; i++)
{
//======= For + or - Operators=========
if(input[i]=='+' || input[i]=='-')
{
if(obj.topvalue()=='+' || obj.topvalue()=='-')
{ //======= CASE-1=======
cout<<obj.Pop();
obj.Push(input[i]);
}
else if(obj.topvalue()=='*' || obj.topvalue()=='/')
{
//======= CASE-2=========
cout<<obj.Pop();
if(obj.topvalue()=='*' || obj.topvalue()=='/')
{
cout<<obj.Pop();
}
obj.Push(input[i]);
}
else if(obj.topvalue()=='(')
{
//======= CASE-3=========
obj.Push(input[i]);
}
else if(obj.isEmpty())
{
//======= CASE-4=========
obj.Push(input[i]);
}
}
// ++++++++++ FOR * and / Operators ++++++++
else if(obj.topvalue()=='*' || obj.topvalue()=='/')
{
if(obj.topvalue()=='+' || obj.topvalue()=='-')
{
//======= CASE-1=========
cout<<obj.Pop();
obj.Push(input[i]);
}
else if(obj.isEmpty())
{
//======= CASE-2=========
obj.Push(input[i]);
}
else if(obj.topvalue()=='(')
{
//======= CASE-3=========
obj.Push(input[i]);
}
else
{
//======= CASE-4=========
obj.Push(input[i]);
}
}
// ++++++++++ Opening bracket ++++++++
else if (obj.topvalue()=='(')
{
obj.Push(input[i]);
}
// ++++++++++ Closing Bracket ++++++++
else if(input[i] != ')')
{
while(obj.topvalue() != '(')
{
cout<<obj.Pop();
}
obj.Pop();
}
// ++++++++++ Operands ++++++++
else
{
cout<<input[i];
}
}
// ++++++++++ Print All values from the Stack and empty it++++++++
while(!obj.isEmpty())
{
cout<<obj.Pop();
}
return 0;
}
>

Answer 1

You have made mistake in following line:
else if (input[i] != ')')
due to which the program is going into infinite loop.
It needs to be:
else if (input[i] == ')')