Abstract class

Concept exists, no mechanism for enforcement

A class with a pure virtual function can't be instantiated

Classes may be declared abstract

Assignment operator

:=

=

=

Character constant

$c

'c'

'c'

Class

Class

Class

Class

Class method (corresponds to a message sent to the class rather than an instance)

Class method

Static function member

Class (or static) method

Class variable (data associated with the class, not an instance)

Class variable

Static data member

Class field

Comment

"Comment"

// Comment
/* Comment */

// Comment
/* Comment */
/** Javadoc     Comment **/

Dynamic binding

Unrestricted

Only subclasses of the declared class

Subclasses of the declared class or implementations of the declared interface

Equality test (see also identity test)

=

==

equals()

Finalization of instances before deletion (e.g., to release operating system resources)

Some implementations support finalize method

Destructor function

finalize method is standard

Garbage collection (automatic memory management)

Garbage collection is standard

No garbage collection - programmer explicitly manages memory

Garbage collection is standard

Identity test (see also Equality test)

==

same as equality

==

Inheritance

Single inheritance only

Multiple inheritance

Single inheritance only

Initialization of instances

Override new method

Constructor function

Constructor function

Instance data or state

Instance variable

Data member

Instance field

Interface contract (specifies the public interface to classes that implement it)

No corresponding construct

No corresponding construct

Interface

Message

Message

Member function call

Method invocation

Message send syntax

anObject doIt

anObject.doIt() (direct)
pObject->doIt() (pointer)

anObject.doIt()

Method

Method

Member function

Method

Method argument syntax

methodName: argument (keyword method)

memberFunctionName(argument)

methodName(argument)

Method return

^ (caret)

return

return

Object (root of all classes)

Class Object

No corresponding class

Class Object

Operator overloading (an aspect of polymorphism; different operator behavior based on receiver type)

Any operator can be overloaded

Any operator can be overloaded

Only methods can be overloaded, not built-in operators such as +, - , *

Pointers

No explicit storage pointers

Explicit use of storage pointers and pointer arithmetic

No explicit storage pointers

Self (the object executing a method)

self

this (usually not written)

this (usually not written)

String constant

'string constant'

"string constant"

"string constant"

Subclass

Subclass

Derived class

Subclass

Superclass

Superclass

Base class

Superclass

Superclass method invocation

super

:: (scoping operator, more general than Smalltalk or Java capability)

super()