a question of const

[chenzy]

What is the difference of the const between Error_code top(Stack_entry &item)const; and Error_code push(const Stack_entry &item); why the first is at the rear and the second is at the front of the item?

[Chervil]

Its the declaration of a constructor for class Queue.
http://www.cplusplus.com/doc/tutorial/classes/

[chenzy]

thanks for your response!! can I ask that what the different between the first queue and the second one? why can't I declare class queue just use class queue??thanks

[Chervil]

what the different between the first queue and the second one?

The first one specifies that this belongs to the class Queue.
The second declares the constructor.

why can't I declare class queue just use class queue?

You can. You only need to declare (and define) a constructor if you want something in particular to happen when the Queue object is created.

The tutorial page is a starting point, but you will probably need additional study material, such as book(s) in order to get a clearer understanding of the topic.

[chenzy]

okay, thanks very much!!