Can a C Class Contain Itself as a Member Variable?

Can a C Class Reference Itself as a Member?

Imagine a scenario where you're working on a C program and desire to create a class that represents expression trees. Within this class, you'd like to define methods to traverse and evaluate the tree in postfix order. However, as you delve into the implementation, you encounter a perplexing issue:

`

<br>class Node {</p>
<pre class="brush:php;toolbar:false">char *cargo;
Node left;
Node right;

};
`

You realize with dismay that you're unable to declare 'left' and 'right' as 'Node' types. This raises a fundamental question: can a C class include itself as a member?

Unveiling the Limitations

The answer to this question is a resounding "no." Declaring the members as 'Node' types creates an infinite recursion. Each Node would contain two other Node objects, which in turn would contain two more Node objects, ad infinitum. This recursive definition leads to an object of infinite size, which is simply not feasible.

Introducing Pointers to the Rescue

Although a class cannot reference itself directly as a member, it can still maintain a reference to itself via pointers. Here's an amended version of your class that addresses this issue:

`

<br>class Node {</p>
<pre class="brush:php;toolbar:false">char *cargo;
Node* left;  // Pointer to a Node
Node* right;  // Pointer to a Node

};
`

By using pointers, you can maintain a tree structure where each node references other nodes in the same class. This allows you to traverse and evaluate the expression tree efficiently without encountering infinite recursion.

The above is the detailed content of Can a C Class Contain Itself as a Member Variable?. For more information, please follow other related articles on the PHP Chinese website!