Vb net validating input
Initial Solution: The Error Provider Component To begin, you need to be aware of the handy Microsoft component called Error Provider (see the MSDN article "Error Provider Component Overview").
Dragging an Error Provider onto the visual designer (or instantiating it in code) gives you the basic component required to display validation messages.
For example, I have inputted '2000', '3746.5', '890' and '567.34'.
After I leave each textbox where I typed in those values, they become '2,000.00', '3,746.50', '890.00', and '567.34'. I have no problem with this, but I do have a problem when it comes to viewing of records.
Instead, it follows the 80/20 rule: The validation engine will be useful in about 80 percent of the use cases you might need to address.
Also following the 80/20 rule, to cover the remaining use cases would require 80 percent of the effort (i.e.
the effort expended to get this far would be multiplied five-fold).
So, for example, you'll find that the engine doesn't handle validation interaction between multiple fields; instead, I opted to focus on single-field validation for this introductory article.
So what happens is after I typed in an amount and left the textbox, the amount (the text I inputted) becomes formatted, and the 'Total' (where the sum is displayed) is automatically updated (I did this using the _Text Changed Event). Note that the method in the example takes a Control as its first argument.That allows the single Error Provider to simultaneously handle error messages for a multiplicity of controls.The second argument to Set Error is the message to display.Passing an empty string tells the Error Provider to suppress the error message indicator completely, so it's important not only to set the error message, but also to remove it when no error condition exists.