Simple validating c input

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When users enter data into your application, you may want to verify that the data is valid before your application uses it.

You may require that certain text fields not be zero-length, that a field be formatted as a telephone number or other type of well-formed data, or that a string not contain any unsafe characters that could be used to compromise the security of a database.

When the user action occurs, you can trigger explicit validation in one of the following ways: However, in some cases, you might want to let the user close the form regardless of whether the values in the controls are valid.

You can override validation and close a form that still contains invalid data by creating a handler for the form's Form Closing event.

The explicit validation approach validates data at one time.

You can validate the data in response to a user action, such as clicking a Save button or a Next link.

A is a string made up of characters from a masking language that specifies which characters can be entered at any given position in the text box. If the user types an incorrect entry, for example, the user types a letter when a digit is required, the control will automatically reject the input.

The masking language that is used by Masked Text Box is very flexible.

In addition, modal forms do not validate the contents of controls when they are closed.The implicit validation approach validates data as the user enters it.You can validate the data as the data is entered in a control by reading the keys as they are pressed, or more commonly whenever the user takes the input focus away from one control and moves to the next.Assigning Disable to the Auto Validate property prevents implicit validation altogether.To validate your controls, you will have to use explicit validation.

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