What happens when calling this non-existent constructor?

Question

When compiling this c++ code, I get an error on the last line.

#include <iostream>

class TestClass {

public:
    TestClass(int val) 
        : value(val)
    {
    }

    int getValue()
    {
        return value;
    }

private:
    int value;

};

int main()
{
    TestClass b();
    std::cout << b.getValue() << std::endl;     
}

The compiler (gcc on Ubuntu 14.04) complains:

error: "request for member ‘getValue’ in ‘b’, which is of non-class type ‘TestClass()’"

Now my question is: What exactly does b contain? The compiler doesn't complain about TestClass b().

It is a function declaration. Plenty of duplicates out there. — juanchopanza, May 18 '15 at 20:02
You're right. Funny that I can make a function declaration within main(), but not a function definition. — jitv, May 18 '15 at 20:16

Jarod42 · Answer 1 · 2015-05-18T20:15:55.803

3

You have a vexing parse with:

TestClass b(); // This is a declaration of function b which return TestClass.

If you have default constructor, use:

TestClass b;

or

TestClass b{};

But as you only have constructor with int parameter do

TestClass b(42);

or

TestClass b{42};

edited May 18 '15 at 20:15

answered May 18 '15 at 20:02

Jarod42

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What happens when calling this non-existent constructor?

1 Answers1