The RangeValidator:

The Validation Control Classes

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The BaseValidator Class:
The validation control classes inherit from the BaseValidator class and inherit its properties and methods. Therefore, it would help to take a look at the properties and the methods of this base class, which are common for all the validation controls:
Members Description
ControlToValidate Indicates the input control to validate.
Display Indicates how the error message is shown.
EnableClientScript Indicates whether client side validation will take.
Enabled Enables or disables the validator.
ErrorMessage Error string.
Text Error text to be shown if validation fails.
IsValid Indicates whether the value of the control is valid.
SetFocusOnError It indicates whether in case of an invalid control, the focus should switch to the related input control.
ValidationGroup The logical group of multiple validators, where this control belongs.
Validate() This method revalidates the control and updates the IsValid property.

The RequiredFieldValidator:
The RequiredFieldValidator control ensures that the required field is not empty. It is generally tied to a text box to force input into the text box.
The syntax for the control:

The RangeValidator:
The RangeValidator control verifies that the input value falls within a predetermined range.
It has three specific properties:
Properties Description
Type it defines the type of the data; the available values are: Currency, Date, Double, Integer and String
MinimumValue it specifies the minimum value of the range
MaximumValue it specifies the maximum value of the range

The syntax for the control:

The CompareValidator:
The CompareValidator control compares a value in one control with a fixed value, or, a value in another control.
It has the following specific properties:
Properties Description
Type it specifies the data type
ControlToCompare it specifies the value of the input control to compare with
ValueToCompare it specifies the constant value to compare with
Operator it specifies the comparison operator, the available values are: Equal, NotEqual, GreaterThan, GreaterThanEqual, LessThan, LessThanEqual and DataTypeCheck

The basic syntax for the control:

The RegularExpressionValidator
The RegularExpressionValidator allows validating the input text by matching against a pattern against a regular expression. The regular expression is set in the ValidationExpression property.
The following table summarizes the commonly used syntax constructs for regular expressions:
Character Escapes Description
\b Matches a backspace
\t Matches a tab
\r Matches a carriage return
\v Matches a vertical tab
\f Matches a form feed
\n Matches a new line
\ Escape character
Apart from single character match, a class of characters could be specified that can be matched, called the meta characters.
Metacharacters Description
. Matches any character except \n
[abcd] Matches any character in the set
[^abcd] Excludes any character in the set
[2-7a-mA-M] Matches any character specified in the range
\w Matches any alphanumeric character and underscore
\W Matches any non-word character
\s Matches whitespace characters like, space, tab, new line etc.
\S Matches any non-whitespace character
\d Matches any decimal character
\D Matches any non-decimal character
Quantifiers could be added to specify number of times a character could appear
Quantifier Description
* Zero or more matches
+ One or more matches
? Zero or one matches
{N} N matches
{N,} N or more matches
{N,M} Between N and M matches
The syntax for the control: