c++ constructor and operator problem

Question

I have a problem with constructor and assignment operator. This is my code:

class Class
{
    private:
        double number1;
        double number2;
    public:
        Class(double, double);
        Class& operator=(const Class& n);
}

Class::Class(double n1 = 0.0, double n2 = 0.0)
{
    this->number1 = n1;
    this->number2 = n2;
}

Class& operator=(const Class& n)
{
     this->number1 = n.number1;
     this->number2 = n.number2;
     return *this;
}

int main()
{
    Class n1(2., 3.), n2(7., -1.), n3();

    n2 = n1; // no problem
    n3 = n1; // problem

    return 0;
}

Can you please enlight me, why is there a problem with the second assignment in the main?

Thank you very much

edit: The following error occurs:

[Error] assignment of function 'Complex cislo2()'
[Error] cannot convert 'Complex' to 'Complex()' in assignment

What kind of problem are you experiencing? Compilation error? Run-time error? Can you include the error in your question? — MetaFight, Jul 11 '15 at 11:40
possible duplicate of [What does A a() mean?](http://stackoverflow.com/questions/17713124/what-does-a-a-mean) — amon, Jul 13 '15 at 20:30

score 2 · Accepted Answer · edited Apr 12 '17 at 07:31

2

amon's comment is correct.

To explain it simply, in the sample code you provided:

Class n3();

Defines a function that takes no arguments, and returns an instance of Class by value.

It is a quirk in the C++ syntax.

To workaround this error, omit the empty parenthesis pair when initializing variables that does not take any constructor parameters.

edited Apr 12 '17 at 07:31

Community

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answered Jul 11 '15 at 12:09

rwong

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You can also get in the habit of using braces to call the constructor in >= C++11. SomeType t{}; – Matthew James Briggs Jul 11 '15 at 17:09

c++ constructor and operator problem

1 Answers1