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.NET/ASP.NET Interview Question - How many validators do ASP.NET have?


    Answer:
     

    A validator is a computer program used to check the validity or syntactical correctness of a fragment of code or text.

    IN ASP.NET there are six different types of Validators.

    1.Required Field Validator.
    2.Regular Expression Validator.
    3.Compare Validator.
    4.Range Validator.
    5.CustomValidator.
    6.Validation Summary

    RequiredFieldValidator:-Ensure that the control has a value to assign in it or user does not skip an entry.

    For Example:- 

     <asp:Textbox id="txtMobileNumber" runat="server"></asp:Textbox>
     <asp:RequiredFieldValidator id="RequiredFieldValidator1" runat="server"
     ControlToValidate="txtMobileNumber"
     ErrorMessage="Mobile Number is a required field."
     ForeColor="Red">
     </asp:RequiredFieldValidator>

     

    Regular ExpressionValidator:-Ensure that the value of the control matches the expression of validator that is specified. This type of validation enables you to check for sequence of character, such as e-mail address, telephone number, postal code and so on.

    For Example:- 

     <asp:TextBox ID="txtE-Mail" runat="server"></asp:TextBox>
     <asp:RegularExpressionValidator ID="RegularExpressionValidator1" runat="server" 
     ControlToValidate="txtPassword"
     ErrorMessage="Please Enter a Valid E-Mail" 
     ValidationExpression="\w+([-+.']\w+)*@\w+([-.]\w+)*\.\w+([-.]\w+)*"> // for internet E-Mail.
     </asp:RegularExpressionValidator>


    CompareValidator:-
    Ensure that the value of one control should be equal to value of another control.which is commonly used in password,less than,greater than or equal to.

    For Example:-

    <asp:TextBox ID="txtPassword" runat="server"></asp:TextBox>
    <asp:TextBox ID="txtConfirmPassword" runat="server"></asp:TextBox>
    <asp:CompareValidator ID="CompareValidator1" runat="server" 
    ControlToCompare="txtPassword" ControlToValidate="txtConfirmPassword" 
    ErrorMessage="Password does not match">
    </asp:CompareValidator>


    RangeValidator:-
    Ensures that the value of the control is in specified lower and upper boundaries or specified range.  You can check ranges within pairs of numbers, alphabetic characters.

    For Example:- 

    <asp:TextBox ID="txtAmount" runat="server"></asp:TextBox>
    <asp:RangeValidator ID="RangeValidator1" runat="server" 
    ControlToValidate="txtPassword"
    ErrorMessage="RangeValidator" MaximumValue="5000" 
    MinimumValue="100">
    </asp:RangeValidator>>


    CustomValidator:-
    This control is used to perform user defined validations.

    ValidationSummary:-This validator is used to displays a detailed summary on the validation errors that currently exist.

    Answer:
     

    A validator is a computer program used to check the validity or syntactical correctness of a fragment of code or text.

    IN ASP.NET there are six different types of Validators.

    1.Required Field Validator.
    2.Regular Expression Validator.
    3.Compare Validator.
    4.Range Validator.
    5.CustomValidator.
    6.Validation Summary

    RequiredFieldValidator:-Ensure that the control has a value to assign in it or user does not skip an entry.

    For Example:- 

     <asp:Textbox id="txtMobileNumber" runat="server"></asp:Textbox>
     <asp:RequiredFieldValidator id="RequiredFieldValidator1" runat="server"
     ControlToValidate="txtMobileNumber"
     ErrorMessage="Mobile Number is a required field."
     ForeColor="Red">
     </asp:RequiredFieldValidator>

     

    Regular ExpressionValidator:-Ensure that the value of the control matches the expression of validator that is specified. This type of validation enables you to check for sequence of character, such as e-mail address, telephone number, postal code and so on.

    For Example:- 

     <asp:TextBox ID="txtE-Mail" runat="server"></asp:TextBox>
     <asp:RegularExpressionValidator ID="RegularExpressionValidator1" runat="server" 
     ControlToValidate="txtPassword"
     ErrorMessage="Please Enter a Valid E-Mail" 
     ValidationExpression="\w+([-+.']\w+)*@\w+([-.]\w+)*\.\w+([-.]\w+)*"> // for internet E-Mail.
     </asp:RegularExpressionValidator>


    CompareValidator:-
    Ensure that the value of one control should be equal to value of another control.which is commonly used in password,less than,greater than or equal to.

    For Example:-

    <asp:TextBox ID="txtPassword" runat="server"></asp:TextBox>
    <asp:TextBox ID="txtConfirmPassword" runat="server"></asp:TextBox>
    <asp:CompareValidator ID="CompareValidator1" runat="server" 
    ControlToCompare="txtPassword" ControlToValidate="txtConfirmPassword" 
    ErrorMessage="Password does not match">
    </asp:CompareValidator>


    RangeValidator:-
    Ensures that the value of the control is in specified lower and upper boundaries or specified range.  You can check ranges within pairs of numbers, alphabetic characters.

    For Example:- 

    <asp:TextBox ID="txtAmount" runat="server"></asp:TextBox>
    <asp:RangeValidator ID="RangeValidator1" runat="server" 
    ControlToValidate="txtPassword"
    ErrorMessage="RangeValidator" MaximumValue="5000" 
    MinimumValue="100">
    </asp:RangeValidator>>


    CustomValidator:-
    This control is used to perform user defined validations.

    ValidationSummary:-This validator is used to displays a detailed summary on the validation errors that currently exist.

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    Regards,

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