Stack

[sunilsaxena2010]

Hello.

I am trying to create a stack program in c++.

I created class as follows :

#include <iostream>
using namespace std;

class MyStack{

      public:
             int size;
             int top;;
    
             MyStack();
             MyStack(int x, int y) : size(x), top(-1){};
             ~MyStack(){};

             int stack[size];
             void push(int x);
             int pop();
             void display();
      };

I am getting error : " invalid use of non-static data member `MyStack::size' "

I don't want to make size as static as i want every instance of this class to set it's own size of stack.

Thanks for your help in advance.

Regards,
Sunil

[kevinchkin]

You are trying to declare array of int's based on the size variable which is not known at the compile time. You should never use non-constant variable to declare an array. If you do want to declare an array based on size variable, you should do something like this

class MyStack { 

      public:
          int size ;
          int *arr; 
          
          MyStack(int s = 10) {
                 arr    = NULL ; 
                 size   = s       ; 
                 if (size != 0) { 
                     arr = new int[size] ; 
                 } 
          } 
         ~MyStack() { 
                if (arr != NULL) { 
                      delete [] arr ; 
                } 
          }               
          
} ; 

Hope this helps !