Question

I have found some code that I need to use for my application but there are two lines in it I can’t figure out what exactly do they do and how… Please, either explain them to me or direct me to a link so I can read more about it.

Dict* dcreate(hash_size size, hash_size (*hashfunc) (const char *));

Here I guess it is passing a function as a parameter with it’s parameter in the following bracket!?

hash_size i = dict->hashfunc(key) % dict->size;

and here, my guess is as good as my dog’s!

The hashfunc:

static hash_size def_hashfunc(const char* key){
    hash_size s = 0;
    while(*key){
        s += (unsigned char) *key++;
    }
return s;
}

Thanks.

Answer 1

For the first line, your guess is correct. That is the header for a function that accepts two arguments, one of which is of the hash_size type, and another which is a pointer to a function whose argument is a const char* and returns a hash_size.

In the second line, dict appears to be a pointer to a struct, so dict->hashfunc(key) calls the function hashfunc, a pointer to which is stored in the dict struct. The last part (... % dict->size) is just the modulo operation.