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If not, it may be possible to perform a cast on the value to change its type and assign it to the variable as the new type.

Successful cast depends on class hierarchy

With regard to reference types, whether or not a cast can be successfully performed depends on the relationship of the classes involved in the classhierarchy.

The generic type Object

A reference to any object can be assigned to a reference variable of the type Object , because the Object class is a superclass of every other class.

In other words, an object instantiated from any class is assignment-compatible with the type Object .

Calling a method on an object

Whether or not a method can be called on a reference to an object depends on the current type of the reference and the location in the class hierarchy where the method is defined.

In order to use a reference of a class type to call a method, the method must be defined at or above that class in the class hierarchy.

Assignment compatibility and type conversion

As background, for understanding runtime polymorphism, you need to understand assignment compatibility and type conversion .

As I mentioned earlier, a value of a given type is assignment-compatible with another type if a value of the first type can be successfully assigned to avariable of the second type.

Type conversion and the cast operator

In some cases, type conversion happens automatically. In other cases, type conversion must be forced through theuse of a cast operator.

A cast operator is a unary operator, which has a single right operand. The physical representation of the cast operator is the name of a type enclosed by apair of matching parentheses, as in:


Applying a cast operator

Applying a cast operator to the name of a variable doesn't actually change the type of the variable. However, it does cause the contents of the variable tobe treated as a different type for the evaluation of the expression in which the cast operator is contained.

Primitive values and type conversion

Assignment compatibility issues come into play for both primitive types and reference types.

Boolean types

To begin with, values of type bool can only be assigned to variables of type bool (you cannot change the type of a bool ). Thus, a value of type bool is not assignment-compatible with a variable of any other type.

Numeric primitive types

In general, numeric primitive values can be assigned to (are assignment-compatible with) a variable of a type whose numeric range is as wideas or wider than the range of the type of the value. In that case, the type of the value is automatically converted to the type of the variable.

For example, types sbyte and short can be assigned to a variable of type int , because type int has a wider range than either type sbyte or type short .

On the other hand, a primitive numeric value of a given type cannot be assigned to (is not assignment-compatible with) a variable of a type with anarrower range than the type of the value.

However, it is possible to use a cast operator to force a type conversion for numeric primitive values.

Questions & Answers

Is there any normative that regulates the use of silver nanoparticles?
Damian Reply
what king of growth are you checking .?
What fields keep nano created devices from performing or assimulating ? Magnetic fields ? Are do they assimilate ?
Stoney Reply
why we need to study biomolecules, molecular biology in nanotechnology?
Adin Reply
yes I'm doing my masters in nanotechnology, we are being studying all these domains as well..
what school?
biomolecules are e building blocks of every organics and inorganic materials.
anyone know any internet site where one can find nanotechnology papers?
Damian Reply
sciencedirect big data base
Introduction about quantum dots in nanotechnology
Praveena Reply
what does nano mean?
Anassong Reply
nano basically means 10^(-9). nanometer is a unit to measure length.
do you think it's worthwhile in the long term to study the effects and possibilities of nanotechnology on viral treatment?
Damian Reply
absolutely yes
how to know photocatalytic properties of tio2 nanoparticles...what to do now
Akash Reply
it is a goid question and i want to know the answer as well
characteristics of micro business
for teaching engĺish at school how nano technology help us
Do somebody tell me a best nano engineering book for beginners?
s. Reply
there is no specific books for beginners but there is book called principle of nanotechnology
what is fullerene does it is used to make bukky balls
Devang Reply
are you nano engineer ?
fullerene is a bucky ball aka Carbon 60 molecule. It was name by the architect Fuller. He design the geodesic dome. it resembles a soccer ball.
what is the actual application of fullerenes nowadays?
That is a great question Damian. best way to answer that question is to Google it. there are hundreds of applications for buck minister fullerenes, from medical to aerospace. you can also find plenty of research papers that will give you great detail on the potential applications of fullerenes.
what is the Synthesis, properties,and applications of carbon nano chemistry
Abhijith Reply
Mostly, they use nano carbon for electronics and for materials to be strengthened.
is Bucky paper clear?
carbon nanotubes has various application in fuel cells membrane, current research on cancer drug,and in electronics MEMS and NEMS etc
so some one know about replacing silicon atom with phosphorous in semiconductors device?
s. Reply
Yeah, it is a pain to say the least. You basically have to heat the substarte up to around 1000 degrees celcius then pass phosphene gas over top of it, which is explosive and toxic by the way, under very low pressure.
Do you know which machine is used to that process?
how to fabricate graphene ink ?
for screen printed electrodes ?
What is lattice structure?
s. Reply
of graphene you mean?
or in general
in general
Graphene has a hexagonal structure
On having this app for quite a bit time, Haven't realised there's a chat room in it.
what is biological synthesis of nanoparticles
Sanket Reply
how did you get the value of 2000N.What calculations are needed to arrive at it
Smarajit Reply
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