C lang Syntax Error missing ";" before "*"

Question

The error appears in the List* next line.

typedef struct {
    List* next;
    int data;
    int index;
} List;

Welcome to SO. There is no type List that is known to the compiler. You cannot use a type before it is defined. You need to use the struct tag if you want to use that type during the declaration: typedef struct List { struct List *next; ...} You might revisit your learning material that introduces linked lists. It should explain that topic. — Gerhardh
– Gerhardh, Commented Jan 11, 2022 at 7:25
This is surely a FAQ. Do we have any post that could be used as canonical dupe? — Lundin
– Lundin, Commented Jan 11, 2022 at 8:00

hyde · Accepted Answer · 2022-01-11 08:06:48Z

3

As noted in comments, the type List is not known when you use it. There are two solutions to this.

The first is to simply use struct List *next:

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

The other is to typedef List into existence before defining struct List.

typedef struct List List;

struct List {
   int n;
   List *next;
};

Which is better is opinion, and thus inappropriate for SO.

hyde

63.2k22 gold badges128 silver badges182 bronze badges

answered Jan 11, 2022 at 7:46

Chris

38.2k6 gold badges33 silver badges59 bronze badges

Sign up to request clarification or add additional context in comments.

1 Answer 1