Textbox
Used for mainly for entering text
Events:
Enter - when user clicks on or tabs into text control
Leave - user chooses another control
Validated - when control finishes validating
Validating - before control validates control
Textchanges - when text has changed
Lets you enter text with keyboard
Supports backspacing, deleting, navigating with cursor keys
Can cut, copy and paste using Clipboard
You can also select part or all of text
Properties
causesValidation - true/false if raises validating event
lines- string array providing access to lines in control
if multiline
passwordChar - character to use for password
multiline true/false
wordwrap true/false
text text inside control
selectedText text user selected
selectionStart beginning of selection
selectionLength number of characters user selected
example
- start new project
- add textbox and button
- double-click the button and add this code:
If TextBox1.SelectionLength = 0 Then
MessageBox.Show("Select some text")
Else
MessageBox.Show(TextBox1.SelectedText & " was selected")
End If
MultiLine textboxes
- Start a new windows project
- Drop textbox on form
- Resize form
- Resize textbox to take up most of the form
- To do this change multiline property to true
- Rename textbox to txtMultiline
- Drop a button below it
- Change text on the button to showLines
- Double click the button
- Add this code
Dim linedata As New System.Text.StringBuilder()
For Each line As String In txtmultiline.lines
linedata.Append(line + vbCrLf)
Next
MessageBox.Show(linedata.ToString())
vbCrLf = new line
Validating textbox
The validation event fires after the user changes focus away from the textbox
This can be done by selecting a different control or closing the form
Validated event occurs after the validating event is done unless it is cancelled
Example- Validating textbox control
- Start a new windows project
- Lay out controls as follows
You want to check that the user entered a number between 1 and 20 and not text
- Double-click button and add this code:
Me.close()
This Closes the app
- Doubleclick validating event on the textbox in property window
- Add this code
Dim num As Integer
If Integer.TryParse(TextBox1.Text, num) Then
If num < 1 Or num > 20 Then
e.Cancel = True
MessageBox.Show("Enter from 1 to 20")
End If
Else
e.Cancel = True
MessageBox.Show("You need an integer")
End If
tryparse() will take the first parameter and put it in the second parameter
if its not a number tryparse returns false
look at the signature
Private Sub TextBox1_Validating(ByVal sender As System.Object, ByVal e As System.ComponentModel.CancelEventArgs) Handles TextBox1.Validating
Inside the e object is a property called cancel
This takes a true or false
You must set this to true if validation fails
You are canceling whatever triggered the event
If e.cancel is false then validation passed
- Add this code to the validated event
MessageBox.Show("Good job You did it")
MaskedTextbox Control
Special kind of textbox
Can limit the data a user enters and formats it automatically
You can auto format it with thousands separators
Make correct length
Mask property determines what the user can and cannot enter into the control
Example:
00/00/00
formats it to 2 numbers. Dash, 2 numbers, dash and 2 numbers
there are also a number of built in masks you can access from the smart tag
choose set mask from the menu
select a mask
mask shows actual value entered in mask for you
preview shows a preview of the mask as the user will see it
allows you to define a pattern to accept user input
Mask-Main Property - the input mask
Textmaskformat-if prompt characters and literal characters are included in the text returned by text property
AsciiOnly-boolean-if true only A-Z and a-z
Mask property
Elements of Default MaskedTextprovider
0 |
Required 0-9 |
9 |
Optional 0-9 |
# |
Optional 0-9, or space, or + or - |
L |
Required Letter A-z or a-z |
? |
Optional letter A-Z or a-z |
& |
Required character |
C |
Optional character |
A,a |
Optional alphanumeric character |
. |
Decimal character |
, |
Thousands placeholder |
: |
Time separator |
/ |
Date Separator |
$ |
Currency Symbol |
< |
Converts all characters after this to lowercase |
> |
Converts all characters after this to uppercase |
| |
Disables previous shift up or down |
\ |
Escape a mask character. Example: \\ is a backslash |
All other characters |
Appear as themselves |
Prompt character is an underscore by default