CODEWITHSUNDEEP
cstruct
Deeven
Deeven

Reputation: 443

Use of struct keyword inside of struct

typedef struct node
{
    int n;
    struct node* next;
}
node;

In the above code there is struct node* next inside the struct node. I don't understand the meaning of it.

Upvotes: 2

Views: 307

Answers (4)

Aske B.
Aske B.

Reputation: 6609

Answering the title: In C, all non-standard types need to be prefaced with the struct keyword:

#include <stdint.h>
typedef uint8_t u8;
typedef uint32_t u32;

struct memory_arena {
    size_t size;
    u8 *base;
    size_t used;
    u32 _savePointCount;
    size_t _savePoints[8];
};

struct application_state {
#if 1
    struct memory_arena globalArena; //<---
#else
    memory_arena globalArena; //Valid C++
#endif
};

If it were in C-style C++, you might find this mixed and matched because it's not required.

Upvotes: 0

Cherubim
Cherubim

Reputation: 5457

In the code there is struct node* next inside the struct node. I don't understand the meaning of it.

Explanation :

A node is a general term used to refer a self referential structure.(click on link to know more)

and going by definition,

A self referential structure is a typical structure whose definition has one or more of its member as a pointer to its own type.

Here in your code next is such a member of the structure struct node which is a pointer to it's own type therefore you see it as a pointer to itself in this manner inside of struct :

struct node* next;

That's the reason why struct keyword is used inside of struct

Purpose of using self referential structures :

self referential structures are very much helpful in building data structures such a linked lists... and in fact the variable next is the very member which is useful in making links between nodes in a linked list :)

Upvotes: 5

user905
user905

Reputation: 260

In simple words, it means that next would also be of the same structure as that of node. So next will also have a field int n and another next.. Also this is dynamic so you don't have to allocate any memory before hand.. you can keep on adding as many node as you want ( you still have to assign memory to each node though -- search for how to use malloc to allocate memory to struct node ) And as it is of pointer type ( struct node* next ) it means you can store the address of your next node in to it and link nodes.. See the linked list implementation for better understanding.. I hope it helps :)

Upvotes: 0

cxw
cxw

Reputation: 17031

struct node* (note the *) is a pointer (*) to a struct node. That means that one node can connect to another, via the pointer, without including the other.

This is referred to as a "linked list" structure. I found a Stanford University tutorial that looks like it covers the subject fairly thoroughly.

Upvotes: 0

Related Questions