output explanation

Question

could someone explain this output please

https://code.sololearn.com/cDUQBqanhI2H/?ref=app

Answer 1

Aymane Boukrouh
I know that but it should invoke a constructor that print something

Answer 2

sneeze
your code has normal case
an object creation invoked some constructors

but in my code I expect to get
A()
A()
B(A)

but I got nothing

Answer 3

There is no output because there is simply no object that is being instantiated.
It seems to be a language paradigm to evaluate whatever possible as a function.
So in this case, the parser thinks you are introducing a function, where the expression
B b( A() );
is a function declaration for a function called "b", which returns an object of type B, and takes a function pointer to a function returning an object of type A with no parameters as its argument.
Due to this evaluation, no object is instantiated and thus no constructor is actually called.

Answer 4

When the legend comes 😍😍

thank you very much it never came to my mind
I got it very well
could you please put some information about "vexing parse" and its synonymous ?

Edited:
could you please adjust my code and define the function and call it

Answer 5

Have a look at my code.

Please read about methods and constructors.

https://code.sololearn.com/c1EbvL6jrQb4

What is the output you wanted ?

https://en.cppreference.com/w/cpp/language/copy_constructor

Answer 6

sneeze
I tried that but in my information A() creates a temporary object check this question please

https://www.sololearn.com/discuss/2028897/?ref=app

A() should be an object creating if we write
A();
like that without passing it as an argument it will call the constructor as expected

but when we pass it I don't know what's happening

also B has just one constructor , if A() is a method that returns something the compiler must show as an error

Answer 7

There is no output

Answer 8

A constructor is not a normal method;

B b;

Creates a object of type B,
The object is called b
This automatically invokes the constructor of type B.

Answer 9

your code is
B b(A());

Code should be :
A a; // create object of type A
B b(a); //create object of type B, give object "a" as parameter

This should print
(A)
(A)
B(A)

Answer 10

First off your work should be mostly done in the main function. Second you need to set up a cout code for what you want to output