CODEWITHSUNDEEP
c
Tom
Tom

Reputation: 9663

Calling a pointer to a function

I'm trying to call a function hfun using a pointer to the function that is held inside a struct.

These are the type definitions:

typedef struct Table* TableP;
typedef struct Object* ObjectP;
typedef int(*HashFcn)(const void *key, size_t tableSize);
typedef struct Object {
    void *key;
    ObjectLink *top;
} Object;

typedef struct Table{
    ObjectLink *linkedObjects;
    size_t size, originalSize;
    HashFcn hfun;
    PrintFcn pfun;
    ComparisonFcn fcomp;
} Table;

And here I'm trying to make the call but get an error that I'm trying to access a place out of memory: 

Boolean InsertObject(TableP table, ObjectP object)
{

    int i = (*table->hfun)(object->key, table->size);
    if (table->linkedObjects[i].key == NULL)
    {
        table->linkedObjects[i].key = object;
    } else
    {
        table->linkedObjects[i].next->key = object;
    }

    return TRUE;
}

Using the Eclipse debugger I can tell that in the point of the call the values of the variables are:

object->key type void* value 0x804c018
table->size type size_t value 1

I guess this isn't the way to call a pointer to a function. What is wrong here?

EDIT:

in the debug i can also see: *table->hfun type int(const void *,size_t) table->hfun type HashFcn value 0x11

Upvotes: 1

Views: 213

Answers (1)

Tom van der Woerdt
Tom van der Woerdt

Reputation: 29985

You're not calling it the right way.

You can access a function pointer just like any other function.

table->hfun(object->key, table->size)

[Edit] Right, make sure you also assign the hfun properly:

int myFunc(const void* key, size_t tableSize) { }

table->hfun = &myFunc;

Upvotes: 7

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