Regular Expressions Hexadecimal RGB color code validation with .net

Hexadecimal RGB color also known as Web colors are colors used in designing web pages. Authors of web pages have a variety of options available for specifying colors for elements of web documents. Colors may be specified as an RGB triplet in hexadecimal format (a hex triplet). A hex triplet is a six-digit, three-byte hexadecimal number used in HTML, CSS, SVG, and other computing applications, to represent colors. It uses sixteen distinct symbols, most often the symbols 0–9 to represent values zero to nine, and A, B, C, D, E, F (or a through f) to represent values ten to fifteen.

We can also use three-digit hexadecimal representation of color in the form #RGB, where RGB is a a three-digit hexadecimal which is expanded to define the six-digit color where each digit is repeated once; thus #RGB defines to the color #RRGGBB.

Regular Expression Pattern

^\#([a-fA-F0-9]{6}|[a-fA-F0-9]{3})$

A description of the regular expression:

Beginning of line or string
A numbered capture group. [[a-fA-F0-9]{6}|[a-fA-F0-9]{3}]
Select from 2 alternatives
Any character in this class: [a-fA-F0-9], exactly 6 repetitions
Any character in this class: [a-fA-F0-9], exactly 3 repetitions
End of line or string

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Regular Expressions Hexadecimal number validation with .net

In mathematics and computer science, hexadecimal (also base-16, hexa, or hex) is a numeral system with a radix, or base, of 16. It uses sixteen distinct symbols, most often the symbols 0–9 to represent values zero to nine, and A, B, C, D, E, F (or a through f) to represent values ten to fifteen.

Regular Expression Pattern

^[a-fA-F0-9]+$

A description of the regular expression:

Beginning of line or string
Any character in this class: [a-fA-F0-9], one or more repetitions
End of line or string

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How we open a File in its Associated Application ?

To open a file in its associated application we have to add namespace to System.Diagnostics.Process to our application. The System.Diagnostics namespace provides classes that allow interacting with system processes, event logs, and performance counters.

Now add below piece of code to any event…

Try
Start(Filename)
Catch ex As Exception
MsgBox(”Trouble starting Application.”, MsgBoxStyle.Information, ” Application Alert”)
End Try

Here we have used Function Start () offer by System.Diagnostics namespace. It Starts a process resource by specifying the name of a document or application file and associates the resource with a new System.Diagnostics.Process component.

Syntax:

Start (ByVal fileName As String)

Parameters:

fileName: The name of a document or application file to run in the process.

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Browsing files in a folder using VB.NET

This small piece of code will give an idea to browse file in a given folder.

Start your VB.NET application and create a new project (Ctrl+Shift+N) in Windows Application and design your form as you like. I have design my form as below (Figure 1.):

Now drag a FolderBrowseDialog from Toolbox and name it FolderBrowserDialog1.

On click event of btnBrowse open FolderBrowserDialog1 to select folder and then assign that path to txtPath.

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Finding Four and(or) Six letter words using regular expressions

In this regular expression we are going to find out All Four to Six letter words. A word is a unit (member) of language that represents a concept which can be expressively communicated with meaning. A word consists of one or more morphemes which are linked more or less tightly together, and has a phonetic value. Get more information about Finding Words using regular expressions.

Regular Expression Pattern

(?<=(?:\s|\G|\A))(\w{4}|\w{6})(?=(?:\s|\Z|\.|\?|\!))

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