CODEWITHSUNDEEP
cstructfunction-pointers
randomThought
randomThought

Reputation: 6393

Function pointer in a struct with same argument type

I am trying to make a struct which has a function pointer for a function that takes the same struct as an argument. I have this at the moment.

typedef struct sharedData
{
    sem_t* forks;
    int id;
    void (*forkFunc)(sharedData*);
};

I am getting errors like

error: expected ‘)’ before ‘*’ token

and warnings like

 warning: no semicolon at end of struct or union 
 warning: useless storage class specifier in empty declaration

What am I doing wrong here?

Upvotes: 4

Views: 1293

Answers (1)

templatetypedef
templatetypedef

Reputation: 373482

The problem is that when you're using typedef struct to introduce a new struct that doesn't require the struct keyword, you cannot refer to the typedef-ed name inside the declaration of the struct. Instead, you need to use the full name for the struct. For example:

typedef struct sharedData
{
    sem_t* forks;
    int id;
    void (*forkFunc)(struct sharedData*);
};

Also, your typedef statement is currently invalid because you haven't given a name by which to call struct sharedData. One way to fix this would be as follows:

typedef struct sharedData
{
    sem_t* forks;
    int id;
    void (*forkFunc)(struct sharedData*);
} sharedData;

Now, you can refer to the struct by the full name struct sharedData or by the shorthand name sharedData.

Upvotes: 8

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