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c++pointerslinked-list
Demigod98
Demigod98

Reputation: 35

What is the difference between this two notations?

So, basically I want to know what is the difference (if there is any) between these two notations:

First example:

struct Node{
int data;
Node* next;
};
Node* head;

Second example:

struct Node{
int data;
struct Node* next;
}
struct Node* head;

I just want to know what's the difference between these two notations, and which is better two use?

Upvotes: 0

Views: 80

Answers (1)

eerorika
eerorika

Reputation: 238311

I want to know what is the difference (if there is any) between these two notations

Node is a type name of a class. It can be used only if the class has been declared. Example:

Node* ptr; // won't work without prior declaration
struct Node;

struct Node;
Node* ptr; // works because of prior declaration

struct Node is the same type name using elaborated type specifier. It is declaration of the class by itself. Example:

struct Node* ptr; // works without prior declaration

Elaborated type specifier can be used to disambiguate when a function and a class have the same name:

struct Node;

void Node();

void foo() {
    Node* ptr;        // this won't work
    struct Node* ptr; // this works
    Node();           // this is a function call
}

Given that in your example the class has already been declared, and there is no ambiguous function, there is no difference other than struct Node is about 64% longer to type.

which is better two use?

Which ever you prefer. Do you like to type more or to type less?

Note about C language: In C, structs do not get a type name automatically, so they can only be referred to using an elaborated type specifier unless the struct has explicitly been given a type name using typedef. This is why you may see elaborated type specifiers used more commonly in C than in C++, as well as typedefs that would be redundant in C++.

Upvotes: 1

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