CSC203_Assign04_1522435_Section01

#include<iostream>
#include<string>
//#include "StackLinkListHeader.cpp"

using namespace std;

class StackList{
private :
   struct Node{
   char value;
   struct Node *next;

   } ;
   struct Node *Head;


public :
StackList()
{
    Head=NULL;
}
~StackList()
{
    Node *tempNode;

    while(Head!=NULL)
    {
        tempNode=Head;
        Head=Head->next;
        delete tempNode;
    }
}

bool IsEmpty()
{
    return Head==NULL;
}
char Pop ()
{
    if(IsEmpty())
    {
        cout << "Error: the Stack is Empty"<<endl;
        return -1;
    }
    else
    {
        char val=Head->value;
         Node *tmpNode;
         tmpNode=Head;
         Head=Head->next;
         delete tmpNode;
         return val;
    }

}


char Top()
{

  if(IsEmpty())
  {
      cout<<"Error:The Stack is empty."<<endl;
  }
  else
  {
      return Head->value;
  }
}

void Push(const char x)
{
   Node *newNode;
   newNode=new Node;
   newNode->value= x;
   newNode->next=Head;
    Head=newNode;                ;

}

};
int Priority(char ele)
    {
        int pri;
        char a,b,c;

        if(ele=='^')
        {
            pri=3;
        }

       else if(ele=='*' || ele=='/' || ele=='%')
        {
            pri=2;
        }
        else
        {
            if(ele=='+' || ele=='-')
            {
                pri=1;
            }
            else
                pri=0;
        }
        return pri;
    }

int main ()
{
    string s;
    cout<<"Please enter an expression: "<<endl;
    getline(cin,s);
    StackList operat;
    StackList append;
    int i;
    int pi;
    int chi;
    char c;
    char k;
    char l;
    char a[10000];
    int m;

    for( i = 0 ; i < s.size() ; i++)
    {
          if(s[i]>='A' && s[i]<='Z' || s[i]>='a' && s[i]<='z' || s[i]>='0' && s[i]<='9')
          {
              append.Push(s[i]);
          }
          else
          {
              if(operat.IsEmpty())
              {
                  operat.Push(s[i]);

              }

              else if(!operat.IsEmpty())
              {
                 pi=Priority(s[i]);

                 c=operat.Top();

                 chi=Priority(c);


                  if(chi<pi)
                  {
                    operat.Push(s[i]);

                  }
                  if(chi==pi)
                  {

                       k=operat.Pop();
                       operat.Push(s[i]);
                       append.Push(k);

                  }

                  if(chi>pi)
                  {
                     while(!operat.IsEmpty() && chi>pi)
                     {
                          k=operat.Pop();
                          append.Push(k);
                     }

                     if(operat.IsEmpty())
                     {
                         operat.Push(s[i]);
                     }

                  }

              }
          }
    }

    while(!operat.IsEmpty())
    {
        l=operat.Pop();
        append.Push(l);

    }


    while(!append.IsEmpty())
    {
      a[m]=append.Pop();

          m++;
    }
    cout<<"Converted postfix expression: "<<endl;
    for(int p=m-1 ; p>=-2; p--)
    {
        cout<<a[p]<<" ";
    }
    cout<<endl;


        return 0;
    }