What does the single asterisk inside parentheses "(*)" do in C++?

Question

I found code that looks like this:

typedef std::map<std::string, Example*(*)()> map_type;

and after searching for a while, I still can't figure out what the (*) operator does exactly. Anyone have any ideas?

Answer 1

The parens here are use to impose precedence. The type

Example*(*)()

is a pointer to function returning pointer to Example.

Without the parens you would have

Example**()

which would be a function returning pointer to pointer to Example.

Answer 2

This is the syntax used to declare a pointer to a function (your case) or an array. Take the declaration

typedef Example* (*myFunctionType)();

this will make the line

typedef std::map<std::string, myFunctionType> map_type;

be exactly equivalent to the line you've given. Note that the difference between Example* (*myFunctionType)() and Example* (*)() is only that the name of the type has been omitted.