I was wondering about a way to get the keyboard strokes & read them. This windows api can be used from all sorts of keylogger hacking tricks to useful shortcut keys in an OS that you would like to define. here is a small code snippet with explanation:

This snippet shows the user how to get the key pressed. That is if the user presses control key that key is identified. Using this we can develop applications with greater flexibility. For example we can make an application to close if a key is pressed and so on.

This code is basically a smaller one with greater potential. It just contains three lines of code.

Source code

Public Declare Function GetAsyncKeyState Lib "user32" (ByVal vKey As Long) As Integer

Source code

On Error Resume Next
 'To check wheteher Control key is pressed
 If GetAsyncKeyState(17) Then
 msgbox "Control key pressed"
 End If

One of my favorite .NET control is the ListView. It is very useful for displaying multiple records on a spreadsheet format. Column sorting is one the feature of spreadsheet applications that most of end-users are used to. Unfortunately, this is not readily available as property in VB.NET. The ListView Sorting property only sorts items and not the sub-items so it can’t be use if we want to allow the user to sort your list by any clicked column.

To make your ListView application capable of column sorting, follow these steps:

1. On your existing project, add a new class with following code:

Source code

Imports System.Collections
Public Class clsListviewSorter
 Implements System.Collections.IComparer ' Implements a comparer Implements IComparer 
 Private m_ColumnNumber As Integer
 Private m_SortOrder As SortOrder
 Public Sub New(ByVal column_number As Integer, ByVal sort_order As SortOrder)
 m_ColumnNumber = column_number
 m_SortOrder = sort_order
 End Sub
 ' Compare the items in the appropriate column 
 Public Function Compare(ByVal x As Object, ByVal y As Object) As Integer Implements IComparer.Compare
 Dim item_x As ListViewItem = DirectCast(x, ListViewItem)
 Dim item_y As ListViewItem = DirectCast(y, ListViewItem)
 ' Get the sub-item values. 
 Dim string_x As String
 If item_x.SubItems.Count <= m_ColumnNumber Then
 string_x = ""
 Else
 string_x = item_x.SubItems(m_ColumnNumber).Text
 End If
 Dim string_y As String
 If item_y.SubItems.Count <= m_ColumnNumber Then
 string_y = ""
 Else
 string_y = item_y.SubItems(m_ColumnNumber).Text
 End If
 ' Compare them. 
 If m_SortOrder = SortOrder.Ascending Then
 If IsNumeric(string_x) And IsNumeric(string_y) Then
 Return (Val(string_x).CompareTo(Val(string_y)))
 ElseIf IsDate(string_x) And IsDate(string_y) Then
 Return (DateTime.Parse(string_x).CompareTo(DateTime.Parse(string_y)))
 Else
 Return (String.Compare(string_x, string_y))
 End If
 Else
 If IsNumeric(string_x) And IsNumeric(string_y) Then
 Return (Val(string_y).CompareTo(Val(string_x)))
 ElseIf IsDate(string_x) And IsDate(string_y) Then
 Return (DateTime.Parse(string_y).CompareTo(DateTime.Parse(string_x)))
 Else
 Return (String.Compare(string_y, string_x))
 End If
 End If
 End Function
End Class

2. Declare a private variable on the form where the listview you want to be sorted is located.

Source code

Private m_SortingColumn As ColumnHeader

3. Then on the listview’s ColumnClick event, add the following code

Source code

Private Sub ListView1_ColumnClick(ByVal sender As Object, ByVal e As System.Windows.Forms.ColumnClickEventArgs) Handles ListView1.ColumnClick
 ' Get the new sorting column. 
 Dim new_sorting_column As ColumnHeader = ListView1.Columns(e.Column)
 ' Figure out the new sorting order. 
 Dim sort_order As System.Windows.Forms.SortOrder
 If m_SortingColumn Is Nothing Then
 ' New column. Sort ascending. 
 sort_order = SortOrder.Ascending
 Else ' See if this is the same column. 
 If new_sorting_column.Equals(m_SortingColumn) Then
 ' Same column. Switch the sort order. 
 If m_SortingColumn.Text.StartsWith("> ") Then
 sort_order = SortOrder.Descending
 Else
 sort_order = SortOrder.Ascending
 End If
 Else
 ' New column. Sort ascending. 
 sort_order = SortOrder.Ascending
 End If
 ' Remove the old sort indicator. 
 m_SortingColumn.Text = m_SortingColumn.Text.Substring(2)
 End If
 ' Display the new sort order. 
 m_SortingColumn = new_sorting_column
 If sort_order = SortOrder.Ascending Then
 m_SortingColumn.Text = "> " & m_SortingColumn.Text
 Else
 m_SortingColumn.Text = "< " & m_SortingColumn.Text
 End If
 ' Create a comparer. 
 ListView1.ListViewItemSorter = New clsListviewSorter(e.Column, sort_order)
 ' Sort. 
 ListView1.Sort()
 End Sub

There you have it, test your listview application and it should be sorting by the column clicked.

All the patterns:

0 MM/dd/yyyy 08/22/2006
1 dddd, dd MMMM yyyy Tuesday, 22 August 2006
2 dddd, dd MMMM yyyy HH:mm Tuesday, 22 August 2006 06:30
3 dddd, dd MMMM yyyy hh:mm tt Tuesday, 22 August 2006 06:30 AM
4 dddd, dd MMMM yyyy H:mm Tuesday, 22 August 2006 6:30
5 dddd, dd MMMM yyyy h:mm tt Tuesday, 22 August 2006 6:30 AM
6 dddd, dd MMMM yyyy HH:mm:ss Tuesday, 22 August 2006 06:30:07
7 MM/dd/yyyy HH:mm 08/22/2006 06:30
8 MM/dd/yyyy hh:mm tt 08/22/2006 06:30 AM
9 MM/dd/yyyy H:mm 08/22/2006 6:30
10 MM/dd/yyyy h:mm tt 08/22/2006 6:30 AM
10 MM/dd/yyyy h:mm tt 08/22/2006 6:30 AM
10 MM/dd/yyyy h:mm tt 08/22/2006 6:30 AM
11 MM/dd/yyyy HH:mm:ss 08/22/2006 06:30:07
12 MMMM dd August 22
13 MMMM dd August 22
14 yyyy’-‘MM’-‘dd’T’HH’:’mm’:’ss.fffffffK 2006-08-22T06:30:07.7199222-04:00
15 yyyy’-‘MM’-‘dd’T’HH’:’mm’:’ss.fffffffK 2006-08-22T06:30:07.7199222-04:00
16 ddd, dd MMM yyyy HH’:’mm’:’ss ‘GMT’ Tue, 22 Aug 2006 06:30:07 GMT
17 ddd, dd MMM yyyy HH’:’mm’:’ss ‘GMT’ Tue, 22 Aug 2006 06:30:07 GMT
18 yyyy’-‘MM’-‘dd’T’HH’:’mm’:’ss 2006-08-22T06:30:07
19 HH:mm 06:30
20 hh:mm tt 06:30 AM
21 H:mm 6:30
22 h:mm tt 6:30 AM
23 HH:mm:ss 06:30:07
24 yyyy’-‘MM’-‘dd HH’:’mm’:’ss’Z’ 2006-08-22 06:30:07Z
25 dddd, dd MMMM yyyy HH:mm:ss Tuesday, 22 August 2006 06:30:07
26 yyyy MMMM 2006 August
27 yyyy MMMM 2006 August

The patterns for DateTime.ToString ( ‘d’ ) :

0 MM/dd/yyyy 08/22/2006
The patterns for DateTime.ToString ( ‘D’ ) :
0 dddd, dd MMMM yyyy Tuesday, 22 August 2006

The patterns for DateTime.ToString ( ‘f’ ) :

0 dddd, dd MMMM yyyy HH:mm Tuesday, 22 August 2006 06:30
1 dddd, dd MMMM yyyy hh:mm tt Tuesday, 22 August 2006 06:30 AM
2 dddd, dd MMMM yyyy H:mm Tuesday, 22 August 2006 6:30
3 dddd, dd MMMM yyyy h:mm tt Tuesday, 22 August 2006 6:30 AM
The patterns for DateTime.ToString ( ‘F’ ) :
0 dddd, dd MMMM yyyy HH:mm:ss Tuesday, 22 August 2006 06:30:07
The patterns for DateTime.ToString ( ‘g’ ) :
0 MM/dd/yyyy HH:mm 08/22/2006 06:30
1 MM/dd/yyyy hh:mm tt 08/22/2006 06:30 AM
2 MM/dd/yyyy H:mm 08/22/2006 6:30
3 MM/dd/yyyy h:mm tt 08/22/2006 6:30 AM
The patterns for DateTime.ToString ( ‘G’ ) :
0 MM/dd/yyyy HH:mm:ss 08/22/2006 06:30:07
The patterns for DateTime.ToString ( ‘m’ ) :
0 MMMM dd August 22
The patterns for DateTime.ToString ( ‘r’ ) :
0 ddd, dd MMM yyyy HH’:’mm’:’ss ‘GMT’ Tue, 22 Aug 2006 06:30:07 GMT
The patterns for DateTime.ToString ( ‘s’ ) :
0 yyyy’-‘MM’-‘dd’T’HH’:’mm’:’ss 2006-08-22T06:30:07

The patterns for DateTime.ToString ( ‘u’ ) :
0 yyyy’-‘MM’-‘dd HH’:’mm’:’ss’Z’ 2006-08-22 06:30:07Z
The patterns for DateTime.ToString ( ‘U’ ) :
0 dddd, dd MMMM yyyy HH:mm:ss Tuesday, 22 August 2006 06:30:07
The patterns for DateTime.ToString ( ‘y’ ) :
0 yyyy MMMM 2006 August
/ Represents the date separator defined in the current DateTimeFormatInfo..::.DateSeparator property. This separator is used to differentiate years, months, and days.
” Represents a quoted string (quotation mark). Displays the literal value of any string between two quotation marks (“). Your application should precede each quotation mark with an escape character (\).
‘ Represents a quoted string (apostrophe). Displays the literal value of any string between two apostrophe (‘) characters.
%c Represents the result associated with a c custom format specifier, when the custom date and time format string consists solely of that custom format specifier. That is, to use the d, f, F, h, m, s, t, y, z, H, or M custom format specifier by itself, the application should specify %d, %f, %F, %h, %m, %s, %t, %y, %z, %H, or %M. For more information about using a single format specifier, see Using Single Custom Format Specifiers.

Building a custom DateTime.ToString Patterns

The following details the meaning of each pattern character. Not the K and z character.
d Represents the day of the month as a number from 1 through 31. A single-digit day is formatted without a leading zero
dd Represents the day of the month as a number from 01 through 31. A single-digit day is formatted with a leading zero

ddd Represents the abbreviated name of the day of the week (Mon, Tues, Wed etc)
dddd Represents the full name of the day of the week (Monday, Tuesday etc)
h 12-hour clock hour (e.g. 7)
hh 12-hour clock, with a leading 0 (e.g. 07)
H 24-hour clock hour (e.g. 19)
HH 24-hour clock hour, with a leading 0 (e.g. 19)
m Minutes
mm Minutes with a leading zero
M Month number
MM Month number with leading zero
MMM Abbreviated Month Name (e.g. Dec)
MMMM Full month name (e.g. December)
s Seconds
ss Seconds with leading zero
t Abbreviated AM / PM (e.g. A or P)
tt AM / PM (e.g. AM or PM
y Year, no leading zero (e.g. 2001 would be 1)
yy Year, leadin zero (e.g. 2001 would be 01)
yyy Year, (e.g. 2001 would be 2001)
yyyy Year, (e.g. 2001 would be 2001)
K Represents the time zone information of a date and time value (e.g. +05:00)
z With DateTime values, represents the signed offset of the local operating system’s time zone from Coordinated Universal Time (UTC), measured in hours. (e.g. +6)
zz As z but with leadin zero (e.g. +06)
zzz With DateTime values, represents the signed offset of the local operating system’s time zone from UTC, measured in hours and minutes. (e.g. +06:00)
f Represents the most significant digit of the seconds fraction; that is, it represents the tenths of a second in a date and time value.
ff Represents the two most significant digits of the seconds fraction; that is, it represents the hundredths of a second in a date and time value.
fff Represents the three most significant digits of the seconds fraction; that is, it represents the milliseconds in a date and time value.
ffff Represents the four most significant digits of the seconds fraction; that is, it represents the ten thousandths of a second in a date and time value. While it is possible to display the ten thousandths of a second component of a time value, that value may not be meaningful. The precision of date and time values depends on the resolution of the system clock. On Windows NT 3.5 and later, and Windows Vista operating systems, the clock’s resolution is approximately 10-15 milliseconds.
fffff Represents the five most significant digits of the seconds fraction; that is, it represents the hundred thousandths of a second in a date and time value. While it is possible to display the hundred thousandths of a second component of a time value, that value may not be meaningful. The precision of date and time values depends on the resolution of the system clock. On Windows NT 3.5 and later, and Windows Vista operating systems, the clock’s resolution is approximately 10-15 milliseconds.
ffffff Represents the six most significant digits of the seconds fraction; that is, it represents the millionths of a second in a date and time value. While it is possible to display the millionths of a second component of a time value, that value may not be meaningful. The precision of date and time values depends on the resolution of the system clock. On Windows NT 3.5 and later, and Windows Vista operating systems, the clock’s resolution is approximately 10-15 milliseconds.
fffffff Represents the seven most significant digits of the seconds fraction; that is, it represents the ten millionths of a second in a date and time value. While it is possible to display the ten millionths of a second component of a time value, that value may not be meaningful. The precision of date and time values depends on the resolution of the system clock. On Windows NT 3.5 and later, and Windows Vista operating systems, the clock’s resolution is approximately 10-15 milliseconds.
F Represents the most significant digit of the seconds fraction; that is, it represents the tenths of a second in a date and time value. Nothing is displayed if the digit is zero.
: Represents the time separator defined in the current DateTimeFormatInfo..::.TimeSeparator property. This separator is used to differentiate hours, minutes, and seconds.