This is a question I just recieved through my "contact" form for this blog. The person (Chris) who asked the question gave a wrong email address, so I will post the answer publicly since I believe this can help other starting sharepoint developers - especially since I saw some wrong tips coming up in google when you search for it. So here is the right way to do it.
Question: "Hi, thanks a mil for those snippets!One question: I'm trying to programatically add selected items of a checkBoxList to a SPListItem, but am not sure in what format it wants it. i.e I've added all items as you suggested - newItem["Name"] = "blah" etc, but when it comes to the field that requires the selected checkboxlist values, I'm stuck."
Answer: to set the value for a check box choice list (a field of type choice, with multiple choices allowed - showing checkboxes), you should use the SPFieldMultiChoiceValue class to set the value. This class allows you to construct the list of choices you want to set for the column by adding the string values to it. Here is an example on how to use it:
SPList sampleList =web.Lists["test"]; SPFieldMultiChoiceValue val = new SPFieldMultiChoiceValue(); val.Add("choice1"); val.Add("choice3"); SPListItem newItem = sampleList.Items.Add(); newItem["Title"] = "This is the new item"; newItem["test"] = val; newItem.Update();