Important Properties of the TextBox Control

The TextBox is one of the handiest and most popular controls in a Windows application. It's a common approach to getting free-form input from the user. You can manipulate a TextBox control's contents and detect changes the user makes to the TextBox through several properties:

• The HideSelection property is True by default and it signifies that the user-highlighted contents of the TextBox will not remain highlighted when focus shifts to another object. If you want the highlighted contents to remain highlighted, just set HideSelection to False.

• The MaxLength property determines the maximum number of characters that the user can enter into the Text property of the TextBox. If you set MaxLength to 0, there is no limit on the number of characters that the user can enter (well, up to 32K, that is)

• The Locked property allows the TextBox to reject user changes but still allows the user to set focus to the TextBox. Therefore, the user can scroll through the contents of a TextBox without accidentally changing anything. Contrast this to the Enabled property which doesn't allow the user to set focus to the TextBox.

• The MultiLine property is only writable at design time, although you can find out its value at runtime. MultiLine is False by default, meaning that everything in the TextBox control will appear on a single line. If MultiLine is set to True, the TextBox will perform word-wrapping and also break a typed line after a hard return.

• The PasswordChar property defines a character that will appear on the screen in place of the actual characters in the Text property. The underlying value of the Text property still contains the actual characters typed by the user, but for each character typed, only the password character will appear. Typically programmers set this property to an asterisk (*) for TextBox controls that represent the password on login screens. If you want to eliminate the PasswordChar property for a TextBox, be careful to erase its old value with your keyboard's Delete key instead of simply overwriting it with the spacebar. A space in the PasswordChar property will cause the user's input to appear as a series of blanks!

• The ScrollBars property is only writable at design time, although you can check its value at runtime. The default value is None, but you can also choose Horizontal, Vertical, or Both. Scrollbars enable the user to scroll vertically through the contents of a multiple line TextBox or horizontally through wide contents of TextBoxes.

• The SelText property assigns or returns the contents of the currently selected text in a TextBox. If you assign a string to SelText property in your code, you'll replace the currently highlighted text with the contents of the new string and deselect whatever had been selected before.

• The SelStart property is an integer value that gives you the position of the first highlighted character in the TextBox. It's zero-based. If there's no text currently selected, SelStart will represent the current position of the text cursor within the TextBox control. If you change the SelStart property in your code, you'll deselect whatever text was highlighted and move the text cursor to the position given by SelStart.

• The SelLength property is an integer that indicates the number of selected characters in the TextBox. You can change SelLength in your code in order to change the number of selected characters. You can also deselect any highlighted characters by setting SelLength to 0.

• The Text property is the TextBox control's default property. You can set it at design time or runtime, and you can also read it at runtime. The Text property represents the current visible, editable (not necessarily visible or editable, depending on the value of the Visible property, Enabled and/or Locked) contents of the TextBox. Since Text is the TextBox control's default property, code such as
  
  txtName = "Elizabeth"
  
  would have the effect of setting the TextBox control's Text property to "Elizabeth."

NOTE: TextBox controls have no Caption property

  

 

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