Place four controls from the Web forms section of the Toolbox onto the form. The one exclusion to this rule is the Custom Validator component.
The associated control is set by right clicking on the validator and selecting Properties from the context menu. The Range Validator control ensures the value inside a control is within a specified range.My code is as follows: I tried it on my own before without the CDbl() part, and I got the same result.I found the above online, and tried it, but I got the same result.I know there is something I am missing, I am just not sure what to add to make it work. Before accepting data from over the network you need to ensure all of the required fields have been filled out and conform to your formats and business rules. NET provides a number of validation controls to ease the burden of performing validation on both sides of the network. To walk along with the example, create a new web application in Visual Studio . Once the application is setup, right click on the empty web form, select Properties from the context menu, and change the Page Layout property to Flow Layout. All of the validation controls must have the Control To Validate property set before rendering the page or the control throws an exception.In the Properties dialog box find the Control To Validate property and select First Name Text Box from the drop down list. We can set other properties, such as the Error Message property, and the final ASPX source code should look like the following. There are four key properties to initialize for a Range Validator.
The cancel button has a Causes Validation property. The Control To Validate property references the ID of the input control to check.
Validation occurs when a user clicks any Button control by default, but you can change this behavior by setting the Causes Validation property to false. The Minimum Value and Maximum Value properties control the allowed range of the input. This property can take one of the following values: String, Integer, Double, Date, or Currency.
I am trying to limit a textbox to a certain range of numbers.
I want someone to be able to type in a number from 0-20. If someone types 21 or higher, it changes it to 20, If someone types 1, and then puts a - in front of it, it will change it to 0.
The problem comes when they delete the number in the box, or put a - with no number (to write -1).
I get this error: A first chance exception of type 'System. Visual and Conversion from string "" to type 'Double' is not valid.