Method Question

Dev Shed Forums Sponsor:

September 4th, 2002, 11:05 PM

justin_dago

Contributing User

Join Date: Apr 2002

Location: new york

Posts: 84

Time spent in forums: < 1 sec
Reputation Power: 12

Method Question

Code:

virtual methodName() = 0;

i've come across this in a book, and i'm wondering what the "= 0" bit is all about

any insight would be greatly appreciated

justin.dago

September 5th, 2002, 09:42 AM

jonsagara

Contributing User

Join Date: Dec 2001

Location: USA

Posts: 286

Time spent in forums: 7 m 23 sec
Reputation Power: 12

If this is C++, then it makes the method a pure virtual function. Any class that contains a pure virtual function cannot be instantiated; you must derive a base class in order to use it.

__________________
Jon Sagara

"Me fail English? That's unpossible!"

September 5th, 2002, 10:34 AM

rendy

Contributing User

Join Date: Jul 2002

Location: London

Posts: 349

Time spent in forums: 4 h 19 m 21 sec
Reputation Power: 11

Remember though that declaring a method pure virtual doesn't mean that it can not have an implementation.

Declaring it pure virtual means that the current class is abstract and that any concrete class inheriting from the surrent class must declare the function as a "normal" virtual function.

__________________
Invoice Software

here

click here

September 5th, 2002, 11:28 PM

justin_dago

Contributing User

Join Date: Apr 2002

Location: new york

Posts: 84

Time spent in forums: < 1 sec
Reputation Power: 12

the = 0 makes it a "pure" virtual function...??

i was not aware there were different types of virtual functions????

September 5th, 2002, 11:31 PM

jonsagara

Contributing User

Join Date: Dec 2001

Location: USA

Posts: 286

Time spent in forums: 7 m 23 sec
Reputation Power: 12

http://msdn.microsoft.com/library/d...tion_Syntax.asp

A pure virtual function MUST be overridden in a base class. A plain virtual function may optionally be overridden.

September 6th, 2002, 09:17 PM

justin_dago

Contributing User

Join Date: Apr 2002

Location: new york

Posts: 84

Time spent in forums: < 1 sec
Reputation Power: 12

great. thanks a lot guys. i'm checking that link now. thanks again.

Developer Shed Advertisers and Affiliates