Class Notes

Vb.Net BCOM 200 Notes

These notes have been adapted with the aid of the Microsoft msdn library, Introduction to .NET Framework by Rajeswari Indupuri, homeandlearn.co.uk, vb.net for dummies … <<list will be extended with full references later>>

Please note the this page will be constantly revised throughout the semester. So please check back regularly.

.NET an Introduction

•       Software platform

•       Language neutral

•       In other words  .NET is not a language it is a Runtime and a library for writing and executing written programs in any compliant language

•       .Net is a new framework for developing web-based and windows-based applications within the Microsoft environment.

•       The framework offers a fundamental shift in Microsoft strategy: it moves application development from client-centric to server-centric.

•       Framework, Languages, And Tools

The .NET Framework: .NET Framework Services

•       Common Language Runtime

•       Windows^® Forms

•       ASP.NET

•       Web Forms

•       Web Services

•       ADO.NET, evolution of ADO

•       Visual Studio.NET

Common Language Runtime (CLR)

•       CLR works like a virtual machine in executing all languages. 

•       All .NET languages must obey the rules and standards imposed by CLR. Examples:

•       Object declaration, creation and use

•       Data types, language libraries

•       Error and exception handling

•       Interactive Development Environment (IDE)

•       Development

•       Mixed language applications

•       Common Language Specification (CLS)

•       Common Type System (CTS)

•       Standard class framework

•       Automatic memory management

•       Consistent error handling and safer execution

•       Potentially multi-platform

•       Deployment      

•       Removal of registration dependency

•       Safety – fewer versioning problems

•       Multiple Language Support

•       CTS is a rich type system built into the CLR it implements various types (int, double, etc) And operations on those types

•       CLS is a set of specifications that language and library designers need to follow. This will ensure interoperability between languages

•       Compilation in .NET

Intermediate Language (IL)

•       .NET languages are not compiled to machine code.  They are compiled to an Intermediate Language (IL).

•       CLR accepts the IL code and recompiles it to machine code.  The recompilation is just-in-time (JIT) meaning it is done as soon as a function or subroutine is called.

•       The JIT code stays in memory for subsequent calls.  In cases where there is not enough memory it is discarded thus making JIT process interpretive.

Languages

•       Languages provided by MS

•       VB, C++, C#, J#, JScript

•       Third-parties are building

•       APL, COBOL, Pascal, Eiffel, Haskell, ML, Oberon, Perl, Python, Scheme, Smalltalk…

Windows Forms

•          Framework for Building Rich Clients

•       RAD (Rapid Application Development)

•       Rich set of controls

•       Data aware

•       ActiveX^® Support

•       Licensing

•       Accessibility

•       Printing support

•       Unicode support

•       UI inheritance

ASP.NET

•       The platform services that allow to program Web Applications and Web Services in any .NET language

•       ASP.NET Uses .NET languages to generate HTML pages. HTML page is targeted to the capabilities of the requesting Browser

•       ASP.NET “Program” is compiled into a .NET class and cached the first time it is called.  All subsequent calls use the cached version.

ASP.NET Web Forms

•       Allows clean cut code

•       Code-behind Web Forms

•       Easier for tools to generate

•       Code within is compiled then executed

•       Improved handling of state information

•       Support for ASP.NET server controls

•       Data validation

•       Data bound grids

Visual Studio.NET

•       Development tool that contains a rich set of productivity and debugging features

•       For this semester we will be using Visual Studio Express Edition 2008 for the VB.Net Language

. Net in Summary

•       Dramatically simplifies development and deployment

•       Provides robust and secure execution environment

•       Supports multiple programming languages

Data types

Visual Basic type	Common language runtime type structure	Nominal storage allocation	Value range
Boolean	Boolean	Depends on implementing platform	True or False
Byte	Byte	1 byte	0 through 255 (unsigned)
Char (single character)	Char	2 bytes	0 through 65535 (unsigned)
Date	DateTime	8 bytes	0:00:00 (midnight) on January 1, 0001 through 11:59:59 PM on December 31, 9999
Decimal	Decimal	16 bytes	0 through +/-79,228,162,514,264,337,593,543,950,335 (+/-7.9...E+28) † with no decimal point; 0 through +/-7.9228162514264337593543950335 with 28 places to the right of the decimal; .smallest nonzero number is +/-0.0000000000000000000000000001 (+/-1E-28) †
Double (double-precision floating-point)	Double	8 bytes	values include -1.79769313486231570E+308 through -4.94065645841246544E-324 † for negative values; 4.94065645841246544E-324 through 1.79769313486231570E+308 † for positive values
Integer	Int32	4 bytes	-2,147,483,648 through 2,147,483,647 (signed)
Long (long integer)	Int64	8 bytes	-9,223,372,036,854,775,808 through 9,223,372,036,854,775,807 (9.2...E+18 †) (signed)
Object	Object (class)	4 bytes on 32-bit platform, 8 bytes on 64-bit platform	Any type can be stored in a variable of type Object
SByte	SByte	1 byte	-128 through 127 (signed)
Short (short integer)	Int16	2 bytes	-32,768 through 32,767 (signed)
Single (single-precision floating-point)	Single	4 bytes	values include -3.4028235E+38 through -1.401298E-45 † for negative values; 1.401298E-45 through 3.4028235E+38 † for positive values
String (variable-length)	String (class)	Depends on implementing platform	0 to approximately 2 billion Unicode characters
UInteger	UInt32	4 bytes	0 through 4,294,967,295 (unsigned)
ULong	UInt64	8 bytes	0 through 18,446,744,073,709,551,615 (1.8...E+19 †) (unsigned)
User-Defined(structure)	(inherits fromValueType)	Depends on implementing platform	Each member of the structure has a range determined by its data type and independent of the ranges of the other members
UShort	UInt16	2 bytes	0 through 65,535 (unsigned)

Arrays

-          Variables that contain a single value are known as a scaler variable, we want to look at variables that contain more than one value or object.

-          An array is a set of values that are logically related to each other, such as the grades of students in the BCOM level 200 class.

-          Basic array syntax: arrayname(n). The array will hold (n+1) objects, we count from 0 to n

-          Multidimensional arrays multidimarray(a,b). The array will hold (a+1) rows with (b+1) columns of objects. We can have up to 32 dimensions of an array. (as at Vb.net 2005). In usual cases we can use up to 3 dimensional arrays, anything more than that is difficult to keep track of in normal use.

-          You declare an array as follows: dim numbersarray(9) as integer.

-          You access an array element by invoking its name and position number after you have declared it, e.g. numbersarray(3)