How to Create/Use Reusable Code

Question

I am reaching the point in my application where I find myself copying code and making slight modifications to it. I realize that there are ways to create code that can be reused. The changes I am making each time I copy the code could be sent as parameters when I call that code.

My problem is that I don't know how to do it or where to put it. I don't know the proper terms to use to research the topic.

I have a C# application with several windows forms. I create new forms and put all my code within the .cs file for those forms. I am working exclusively with private void classes and really need to expand my knowledge.

I hope that some of you can point me in the right direction by telling me the proper terminology for what I'm trying to do so that I can research the topic. Details would be great to, but I'd really appreciate help with terms/names for the things I need to know for creating reusable code within my project.

For a bit of specifics about what I'm doing: I'm using VS2008. My application is an interface to a SQL Express database. I have created code for adding/modifying/deleting records based on user inputs. As I create new forms, I often want to call the same code I have used for other forms. I need to know how to put that code in some global location or class so that it can be called from individual forms and not copied into each form's .cs file.

Thanks.

Len La Sala · Answer

Hi Kernel, What I do is put all my common functions/methods into associated classes, that is non specific code which can be used in multiple forms / applications go into a class I call common.cs or global.cs. I do a lot of SQL work but do not use databound controls so I have a class which handles all of my sql connections, reads, writes, validation etc I call this class sqlCommon As an example, I want to fill list boxes on various forms throughout my application I can either write code for each list box to be filled or write 1 function to do all list boxes regardles of what is to be loaded. obviously you need to provide parameter values to enable you to load any list box. eg. Function in common.cs public void fillListBox(ListBox lb, bool clear, int fromWhere, string sz) { if(clear) { lb.Items.Clear();} switch(fromWhere) case 1: //write code } Call to function in common.cs common.fillListBox(lb, true, 1, "SELECT name FROM customer ORDER BY name") in this case, we are sending the list box to be filled (lb) and to clear the list box of existing items (clear) and to laod from an SQL database (fromWhere) the values retrieved by the SQL statement (sz) Of course you could have variations of the same function for different scenarios but the principles would be the same This is a write once use many times function hope it helps you. www.c-sharplizards.com

Kernel Kurtz · Answer

I got the code to work after resolving one error. Here's a follow-up note that might help someone else. Error message: An object reference is required for the non-static field, method, or property My solution: Changed "public void" to "public static void" Thanks again to Len La Sala

Kernel Kurtz · Answer

Len La Sala, Thanks a lot. Seems so easy now that I see the example. This is really going to clean up my project. Thanks again.

Vijaya Kadiyala · Answer

Instead of making a copy of the code, try to modify the code based on new requirements. Initial to start with you can create Class for all the re-usable code. Thanks Vijaya Kadiyala http :// dotnetvj . blogspot . com

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