Most of the functionality I will need is already in the Microsoft text box class. Web Controls This is how Microsoft sets up their controls, so I am going to run with it for now. Since we are inheriting from the text box, we don’t need it anymore. Net does not support multiple inheritance (for Multi-language compatibility reasons, mainly.) But we can use interfaces, and there is an IValidator interface that will work.
Let’s not reinvent the wheel (See the title of my blog for more info.) We are going to inherit from the standard text box control instead. The text box already knows has a perfectly serviceable text property. So, add to the class declaration so it looks like this: The addition of an interface is like signing a contract.
If you did that, the user could have moved the cursor to the beginning and pressed space. Make sure to check the entire field when you validate, even if you are using the If you don't want to allow any other characters entry except for the alphanumeric characters in a Text Box, then you can do this on the Key Press event of a Text Box. Key Char) If yes, then allow the Key pressing by setting "e.
Label ""Form overrides dispose to clean up the component list.
Text Box Friend With Events txt Last Name As System.
The Data Entry Pattern dialog box offers prebuilt regular expressions for U. and Canadian telephone numbers, social security numbers , 5-digit ZIP Codes, and ZIP 4 Codes, as shown on the left in Figure 8-4.
You can also create your own regular expression by selecting a custom pattern and adding special characters from an Insert Special Character drop-down list.