Validating user input visual basic
A common design pattern in software built with C# and the . This is the standard approach in web applications using the Model View Controller (MVC) libraries. NET frameworks provide functionality to abstract data validation into validation attributes which are used to "decorate" the properties of entity classes. There are standard validation attributes for a number of common data types, such as dates and email addresses.
In the example below, Validation attributes, along with many other data annotations, are found in the System. Data Annotations namespace, which is available in both the . The Data Annotations namespace provides two ways of validating a telephone numbers as a data type, .
In this example, we have redundancy for illustration purposes.
The Web Forms infrastructure provides a selection of validation controls that you can use to validate user input, and display error messages to the user.The built-in validation controls include: * Required Field Validator—Requires an entry in a field * Compare Validator—Compares an entry with a value or a property of another control * Range Validator—Requires an entry to be between specified lower and upper bounds * Regular Expression Validator—Requires an entry to match a pattern specified by a regular expression * Custom Validator—Requires an entry to pass a validation test that you code yourself * Validation Summary—Displays a summary of validation errors for all the validation controls on a page Listing 8.12 presents a simple Web Form that asks for a user's age.It uses the Required Field Validator, Regular Expression Validator, and Range-Validator controls to validate the user's input.Google makes extensive use of phone numbers in its cloud applications, business operations, and in the Android, Chrome, and (presumably) Fuchsia operating systems.
Handling phone numbers effectively is important for security and ease of use in all these software systems.Specify static to create space for the error display whether it is visible or not.