CODEWITHSUNDEEP
c++
user336635
user336635

Reputation: 2281

Difference between * and *&

When I have defined fnc in a following way: 

QDialog* get_dialog(Caller* caller);

then calling it with my class 

class Main_Dialog : public Base_Dialog<Ui::Main_Dialog>{};

works. 

//def of Base_Dialog   

template< class Ui_Dialog >
class Base_Dialog : public QDialog, protected Ui_Dialog{};

but if I define this fnc as: 

QDialog* get_dialog(Caller*& caller);   //note ref

then code doesn't compile, giving error: 

error: no matching function for call to 'Main_Dialog::get_dialog(Main_Dialog* const)'

candidate is: 

template<class Dialog, class Caller> QDialog* Main_Dialog::get_dialog(Caller*&)

Isn't that the fnc I'm trying to call? What's wrong?

Upvotes: 0

Views: 157

Answers (1)

Bj&#246;rn Pollex
Bj&#246;rn Pollex

Reputation: 76788

It looks like you are trying to pass in a const pointer, but the method requires a non-const pointer.

QDialog* get_dialog(Caller*& caller);

This method requires a reference to a pointer (no const anywhere). If you would pass in a non-const pointer, it would implicitly be converted to a reference-to-non-const-pointer. However, if you are passing in a const-pointer, that implicit conversion does not work, so the compiler looks for a function with a signature like:

get_dialog(Main_Dialog* const)

Upvotes: 1

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