SharePoint Tips: Object Mode provides Built-in Field and Content type Ids

  listItem["Title"] = "value";

Code Snippet 1: Usual approach

The title field is SharePoint built-in field and you don’t need to hard-code the field name . SharePoint Object Model provides a class ‘SPBuiltInFieldId'‘ where you can find most of the SharePoint built-in field’s IDs. So you can write the above code snippet as shown below:

  listItem[SPBuiltInFieldId.Title] = "value";

Code snippet 2: Suggested approach to access built-in fields

The class ‘SPBuiltInFieldId‘ also provides many built-in fields Ids like ‘created by’ (known as owner), modified by etc.

Similarly you can get built-in content type Ids using the class ‘SPBuiltInContentTypeId‘. I would recommend you to use these classes to access built-in fields and content types.