Data Type Conversion, File Extensions

Converting between Data types

In Visual Basic, data can be converted in two ways: implicitly, which means the conversion is performed automatically, and explicitly, which means you must perform the conversion.

Implict Conversions

Let's understand implicit conversions in code. The example below declares two variable, one of type double and the other integer. The double data type is assigned a value and is converted to integer type. When you run the code the result displayed is an integer value, in this case the value displayed is 132 instead of 132.31223.

Imports System.Console Module Module1 Sub Main() Dim d=132.31223 as Double Dim i as Integer i=d WriteLine("Integer value is" & i) End Sub End Module

Explicit Conversions

When types cannot be implicitly converted you should convert them explicitly. This conversion is also called as cast. Explicit conversions are accomplished using CType function.

CType function for conversion

If we are not sure of the name of a particular conversion function then we can use the CType function. The above example with a CType function looks like this:

Imports System.Console Module Module1 Sub Main() Dim d As Double d = 132.31223 Dim i As Integer i = CType(d, i) 'two arguments, type we are converting from, to type desired WriteLine("Integer value is" & i) End Sub End Module

Below is the list of conversion functions which we can use in VB .NET.

CBool - use this function to convert to Bool data type
CByte - use this function to convert to Byte data type
CChar - use this function to convert to Char data type
CDate - use this function to convert to Date type
CDbl - use this function to convert to Double data type
CDec - use this function to convert to Decimal data type
CInt - use this function to convert to Integer data type
CLng - use this function to convert to Long data type
CObj - use this function to convert to Object type
CShort - use this function to convert to Short data type
CSng - use this function to convert to Single data type
CString - use this function to convert to String data type

Attributes

Attributes are  those that lets us specify information about the items we are using in VB .NET. Attributes are enclosed in angle brackets(< >) and are used when VB .NET needs to know more beyond the standard syntax.

File Extensions in VB .NET

The files and their extensions which are created as part of the Windows Application Project and their meaning are summarized below:

.vbproj->A Visual Basic project
Form1.vb->A form's code
AssemblyInfo.VB->Information about an assembly, includes version information
.vbproj.user->Stores project user options
.sln->Solution file which stores solution's configuration
.suo-> Stores Solution user options
Form1.resx.NET->XML based resource template
bin directory->Directory for binary executables
obj directory->Directory for debugging binaries

Language Terminology

Briefly on some terminology when working with the language:

Module: Used to hold code
Variable: A named memory location of a specific data type used to hold some value
Procedure: A callable series of statements which may or may not return a value
Sub-Procedure: A procedure with no return value
Function: A procedure with return value
Methods: A procedure built into the class
Constructor: Special method used to initialize and customize the object. It has the same name as the class
Class: An OOP class which contains data and code
Object: An instance of a class
Arrays: Programming constructs that lets us access data by numeric index
Attributes: They are the items that specify information about other items being used in VB. NET