about
Visual basic coding & visual basic hosting - at
BottomLinecom.net |
BottomLine features
hosting on Windows servers. Visual Basic and C and it's
language variants are all native on web severs using the
Microsoft Windows OS.
What's new in Visual
Basic
Visual Basic .NET has many new and improved
language features — such as inheritance, interfaces, and
overloading — that make it a powerful object-oriented
programming language. As a Visual Basic developer, you
can now create multithreaded, scalable applications
using explicit multithreading. Other new language
features in Visual Basic .NET include structured
exception handling, custom attributes, and common
language specification (CLS) compliance.
The CLS is a set of rules that standardizes such
things as data types and how objects are exposed and
interoperate. Visual Basic .NET adds several features
that take advantage of the CLS. Any CLS-compliant
language can use the classes, objects, and components
you create in Visual Basic .NET. And you, as a Visual
Basic user, can access classes, components, and objects
from other CLS-compliant programming languages without
worrying about language-specific differences such as
data types. CLS features used by Visual Basic .NET
programs include assemblies, namespaces, and attributes.
Visual Basic .NET supports many new or improved
object-oriented language features such as inheritance,
overloading, the Overrides keyword, interfaces,
shared members, and constructors.
Also included are structured exception handling,
delegates, and several new data types.
What's New in Visual Basic .NET 2003
Visual Basic .NET 2003 has added functionality that
simplifies bit manipulation and loop variable
declaration.
- Bit Shift Operators
- Visual Basic .NET now supports arithmetic left
and right shift operations on integral data types (Byte,
Short, Integer, and Long).
Arithmetic shifts are not circular, which means the
bits shifted off one end of the result are not
reintroduced at the other end. The corresponding
assignment operators are provided as well. For
details, see
Bit Shift Operators and
Assignment Operators.
- Loop Variable Declaration
- Visual Basic .NET now allows you to declare a
loop variable as part of a For or For Each
loop. You can include an As clause for the
variable in the For or For Each
statement, provided no variable of that name has
been declared outside the loop. The scope of a loop
variable declared in this manner is the loop itself.
For details, see
For...Next Statements and
For Each...Next Statements.
What's New in Visual Basic .NET 2002
Visual Basic .NET 2003 also includes the following
features, which were introduced in Visual Basic .NET
2002.
- Inheritance
- Visual Basic .NET supports inheritance by
allowing you to define classes that serve as the
basis for derived classes. Derived classes inherit
and can extend the properties and methods of the
base class. They can also override inherited methods
with new implementations. All classes created with
Visual Basic .NET are inheritable by default.
Because the forms you design are really classes, you
can use inheritance to define new forms based on
existing ones. For details, see
Inheritance.
- Exception Handling
- Visual Basic .NET supports structured
exception handling, using an enhanced version of
the Try...Catch...Finally syntax supported by
other languages such as C++. Structured exception
handling combines a modern control structure
(similar to Select Case or While) with
exceptions, protected blocks of code, and filters.
Structured exception handling makes it easy to
create and maintain programs with robust,
comprehensive error handlers. For details, see
Exception Handling.
- Overloading
- Overloading is the ability to define
properties, methods, or procedures that have the
same name but use different data types. Overloaded
procedures allow you to provide as many
implementations as necessary to handle different
kinds of data, while giving the appearance of a
single, versatile procedure. For details, see
Overloaded Properties and Methods.
- Overriding Properties and Methods
- The Overrides keyword allows derived
objects to override characteristics inherited from
parent objects. Overridden members have the same
arguments as the members inherited from the base
class, but different implementations. A member's new
implementation can call the original implementation
in the parent class by preceding the member name
with MyBase. For details, see
Overriding Properties and Methods.
- Constructors and Destructors
- Constructors are procedures that control
initialization of new instances of a class.
Conversely, destructors are methods that free
system resources when a class leaves scope or is set
to Nothing. Visual Basic .NET supports
constructors and destructors using the Sub New
and Sub Finalize procedures. For details, see
Object Lifetime: How Objects are Created and
Destroyed.
- Data Types
- Visual Basic .NET introduces three new data
types. The Char data type is an unsigned
16-bit quantity used to store Unicode characters. It
is equivalent to the .NET Framework System.Char
data type. The Short data type, a signed
16-bit integer, was named Integer in earlier
versions of Visual Basic. The Decimal data
type is a 96-bit signed integer scaled by a variable
power of 10. In earlier versions of Visual Basic, it
was available only within a Variant. For
details, see
Data Types.
- Interfaces
- Interfaces describe the properties and
methods of classes, but unlike classes, do not
provide implementations. The Interface
statement allows you to declare interfaces, while
the Implements statement lets you write code
that puts the items described in the interface into
practice. For details, see
Interfaces in Visual Basic .NET.
- Delegates
- Delegates — objects that can call the
methods of objects on your behalf — are sometimes
described as type-safe, object-oriented function
pointers. You can use delegates to let procedures
specify an event handler method that runs when an
event occurs. You can also use delegates with
multithreaded applications. For details, see
Delegates and the AddressOf Operator.
- Shared Members
- Shared members are properties,
procedures, and fields that are shared by all
instances of a class. Shared data members are useful
when multiple objects need to use information that
is common to all. Shared class methods can be used
without first creating an object from a class. For
details, see
Shared Members.
- References
- References allow you to use objects
defined in other assemblies. In Visual Basic .NET,
references point to assemblies instead of type
libraries. For details, see
References and the Imports Statement.
- Namespaces
- Namespaces prevent naming conflicts by
organizing classes, interfaces, and methods into
hierarchies. For details, see
Namespaces.
- Assemblies
- Assemblies replace and extend the
capabilities of type libraries by, describing all
the required files for a particular component or
application. An assembly can contain one or more
namespaces. For details, see
Assemblies.
- Attributes
- Attributes enable you to provide
additional information about program elements. For
example, you can use an attribute to specify which
methods in a class should be exposed when the class
is used as a XML Web service. For details, see
Attributes.
- Multithreading
- Visual Basic .NET allows you to write
applications that can perform multiple tasks
independently. A task that has the potential of
holding up other tasks can execute on a separate
thread, a process known as multithreading. By
causing complicated tasks to run on threads that are
separate from your user interface, multithreading
makes your applications more responsive to user
input. For details, see
Multithreaded Applications.
|
|
|