Suppose we have a class called widget defined in widget.hpp
class widget
{
...
};
How many ways (exclusing templates) can the definition of the class fubar depend on widget?I can think of thirteen ways:
class fubar : public widget // 1 inheritance
{
void value_parameter(widget ); // 2
void ref_parameter(widget &); // 3
void ptr_parameter(widget *); // 4
widget value_return(); // 5
widget & ref_return(); // 6
widget * ptr_return(); // 7
widget instance_value_member; // 8
widget & instance_ref_member; // 9
widget * instance_ptr_member; // 10
static widget static_value_member; // 11
static widget & static_ref_member; // 12
static widget * static_ptr_member; // 13
};
Now for the test.Which of the thirteen ways require a hash include
#include "widget.hpp"as opposed to a forward declaration
class widget;I've given this test to many many programmers and the vast majority get it wrong. The variety of answers I get is amazing. I recently gave it to a room of about 100 C++ developers and 5 got it right with about 20 different wrong answers (at which point I stopped counting).
What's your answer?
Once you've decided you can scroll down to find the answer.
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The answer is 1 and 8.
How did you do?
If you don't believe me why not try it now in cyber-dojo (click the link and then click the start button).
