Input errors, such as an incorrect email address, will be indicated using the web browser dialogs as in the previous example.
attribute allows the use of regular expressions to specify custom formats for the input.
The next region contains the class methods; this region contains an On Paint event handler which is in its default condition and it contains a validation method which is used to validate the content of the text box against the user supplied regular expression: In the example provided above, the control is validating the text against a regular expression used to validate a social security number; if the validate control function returns a false, the user is shown the correct format for a valid entry.
This click event handler calls the Perform Form Validation method; the returned value is used to set a boolean and the boolean is then evaluated and if true, the application exists, if not the user is shown a message instructing them to fix the errors before closing the form.
This is useful for specific types of data patterns such as telephone numbers, postal codes, and serial numbers.
In the example below, the element specifies a particular format that matches car license plate (registration) numbers in Germany.
Depending on your web browser, the “Range” input field will be displayed as a slider control to help users provide input more easily.
Most current web browsers automatically set its value to .The first project is a class library called "Reg Ex Controls" which contains a class called "Reg Ex Text Box"; this class is an extended text box control that provides the means to store a regular expression and to test the text box text against the regular expression.The second project is a test windows form application called "Test Reg Ex Controls"; this project contains a single windows form that shows five examples of the extended text box control in use in conjunction with an error control.In addition to providing instructions, validate user input to help users avoid mistakes.HTML5 defines a range of built-in functionality to validate common types of input, such as email addresses and dates.
Most current web browsers support these features and handle input validation.