C++ code for infix to postfix conversion

#include <iostream>
using namespace std;
class InToPost
{
   char *infx,*pofx,*s,ch,elem;
   int top,size;
   int i,j;
   char temp;
   public:
	
     void push(char elem);
     char pop();
     void convert();
     int prec(char elem);
     InToPost()
     {
	top = -1;
	cout<<"enter size of the string"<<endl;
	cin>>size;
	infx=new char[size]; 
	pofx=new char[size];
	s=new char[size];
	cout<<"read the infix expression ? ";
	cin>>infx;
     }
};
void InToPost::push(char elem) 
{
 s[top] = elem;
 top++;
}


char InToPost:: pop() 	
{
    top--;
 return (s[top]);
}

/* Write code in convert() to convert infix to postfix expr */
int InToPost::prec(char elem)
{
    if(elem=='(')
    {
        return 1;
    }
    if(elem=='+'||elem=='-')
    {
        return 2;
    }
    if(elem=='*'||elem=='/')
    {
        return 3;
    }
}
void InToPost::convert()
{
    for(i=0;i<size;i++)
    {
        if(infx[i]!='+'&&infx[i]!='-'&&infx[i]!='*'&&infx[i]!='/'&&infx[i]!='(')
        {
            pofx[j++]=infx[i];
        }
        else
        {
            if(top==0)
            {
                push(infx[i]);
            }
            else
            {
                if(infx[i]!='(')
                {
                    if(prec(infx[i])<=prec(s[top-1]))
                    {
                        temp=pop();
                        pofx[j++]=temp;
                        push(infx[i]);
                    }
                    else
                    {
                        push(infx[i]);
                    }
                }
                    else
                    {
                        if(infx[i]=='(')
                        {
                            push(infx[i]);
                        }
                    }
                }
            }
        }
        while(top!=0)
        {
            pofx[j++]=pop();
        }
        cout<<infx<<endl;
        cout<<pofx<<endl;
}
/*
  Write code here to find the precedence of the operators as indicated below
  # = 0, ( = 1, +,- = 2, *,/ = 3 using function int prec(char elem);
*/


int main()
{
 char ch;
 int i = 0, k = 0;
 InToPost ip;
 ip.push('#');
 ip.convert();
 return 0;
}