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cstructuretypedef

How to typedef a structure including pointers to itself?

Code without typedef (and it works):

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

I'm trying to make a code using typedef for the structure "Node" in Doubly Linked List, but this does not work:

typedef struct {
    int data;
    Node *next;
    Node *prev;
} Node;

Is there a way around this using typedef?

Solution

  • Inside the typedef, the to-be-defined type is not yet known, so you need to introduce and use a struct tag:

    typedef struct Node_tag {
    int data;
    struct Node_tag *next;
    struct Node_tag *prev;
} Node;

    The Node_tag is the struct tag, because of where it is introduced (and not because of the name part "_tag"). It is not a type in itself, only the combination as struct Node_tag is a type which can be used for the struct members.
    Afterwards, when the typedef is done, the type Node has been defined.
    To clarify, a second typedef would be possible as typedef struct Node_tag NodeToo;. This demonstrates that the type struct Node_tag is also useable. That is why I prefer to use the "_tag" name fragment, to allow to be clear of what is used.