CODEWITHSUNDEEP
c++syntax
lissachen
lissachen

Reputation: 229

What does the (*) syntax in C++ mean?

What does the following syntax mean?

set<element*, bool (*) (element *, element *)> * getNumbers();

I'm not familiar with the (*) part. Any explanation would be great. Thanks

Upvotes: 9

Views: 17223

Answers (5)

Jan Groothuijse
Jan Groothuijse

Reputation: 320

It is a function pointer, more precisely bool (*) (element *, element *) is the type of a function pointer. In this case its a function that takes two element pointers and returns a bool.

Its makes more sense when you see it used as function parameter, then it will have a name after the first *. For example bool (*fun) (element *, element *).

Upvotes: 2

molbdnilo
molbdnilo

Reputation: 66371

Here it means that the second template parameter is a function pointer:

bool (*) (element *, element *)

is "pointer to a function that takes two element*s and returns bool".

You may also see (*) in connection with pointers to arrays;

int (*) [32]

is the type "pointer to an array of 32 ints".

Upvotes: 10

Starl1ght
Starl1ght

Reputation: 4493

Second template argument is function pointer, designed to compare 2 element*. If you put such function pointer in constructor of std::set - you will be able to create set of elements with custom compare function (or without overloaded operator<).

Upvotes: 0

aschepler
aschepler

Reputation: 72271

bool (*) (element *, element *) names the type of a pointer to function, where the function takes two element* pointers as parameters and returns a bool.

Upvotes: 0

Guy Kogus
Guy Kogus

Reputation: 7341

It's a function pointer. You can read about it further here, for example: http://www.cprogramming.com/tutorial/function-pointers.html

Upvotes: 0

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