Validation By Control ASP.Net

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  4. Define your own logic with CustomValidator
<%@ Page Language="C#"%>


protected void ServerAddMoreValidation(object o, ServerValidateEventArgs e) {
    try {
        int theInput = Int32.Parse(e.Value);
        if (theInput < 0) {
            theValidator.ErrorMessage = "please enter a positive value";
        }
        else {
            theValidator.ErrorMessage = "please enter at least " + (theInput + 1).ToString();
        }
    }
    catch {
    }
    e.IsValid = false;
}



    Target Page



Enter the quantity:

    runat="server"
    id="theValidator" 
    ControlToValidate="quantity"
    OnServerValidate="ServerAddMoreValidation" 
    ErrorMessage="Try Again"/>