Before looking at the code, Read about – What is JumpStart?
<%@ Page Language="C#" %> <%@ Import Namespace="System.Runtime.InteropServices" %> <!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd"> <script runat="server"> protected void Page_Load(object sender, EventArgs e) { // Call with only name optionalParameterMethod("John"); //call with name and state optionalParameterMethod("Scott", "AK"); //call with name, state and city optionalParameterMethod("Chris", "FL", "Miami"); //call with name and city optionalParameterMethod("Alan", city: "BayArea"); //call with name, state and city with Named Parameters optionalParameterMethod("Bob", state: "Calif" ,city: "BayArea"); /* cannot call method like the following with missing Required Parameter optionalParameterMethod(state:"Hi",city: "Hello"); */ // Call with only name optionalParameterAttMethod("John"); //call with name and state optionalParameterAttMethod("Scott", "AK"); //call with name, state and city optionalParameterAttMethod("Chris", "FL", "Miami"); //call with name and city optionalParameterAttMethod("Alan", city: "BayArea"); //call with name, state and city with Named Parameters optionalParameterAttMethod("Bob", state: "Calif", city: "BayArea"); /* cannot call method like the following with missing Required Parameter optionalParameterAttMethod(state:"Hi",city: "Hello"); */ } protected void optionalParameterMethod(string name, string state = "CA", string city = "SFO") { /* Use the parameters here. This is a feature of C# 4.0 * If not Values are supplied to parameters, then they contain default values i.e., CA , SFO */ Response.Write(name + "---" + state + "---" + city); Response.Write("<br/>"); } protected void optionalParameterAttMethod(string name, [Optional,DefaultParameterValue("CA")] string state, [Optional] string city) { /* To implement Optional Att - import System.Runtime.InteropServices namespace * If not Values are supplied to parameters, then they contain default values i.e., null */ Response.Write(name + "---" + state + "---" + city); Response.Write("<br/>"); } </script> <html xmlns="http://www.w3.org/1999/xhtml"> <head id="Head1" runat="server"> <title></title> </head> <body> <form id="form1" runat="server"> <div> </div> </form> </body> </html>
Appendix -
- state: "Calif", city: "BayArea" – These are called as Named Parameters. Those calls improve readability. Lessen burdens on the developers to memorize the order of parameters.
- Be careful in using Optional Parameters – as they are substituted with their default values. So the logic must be good enough in case of using optional parameters.
- [Optional,DefaultParameterValue(“CA”)] – also serves as optional parameters. But we got to import System.Runtime.InteropServices.
