First of all, you must respect every license or copyright that exists. If there is none (as with many homepages and so on), just assume a full copyright with no license. If it is a tutorial, of course you can use it to write your own code, but always give credit to the original code, and include a reference.

Bottom line, if you want to call it your own code, write it from scratch. Just begin with an empty file, and only copy things from manuals that came with the program/ compiler / etc, or if you take something out of a tutorial, put in a reference and credit.

There is no such thing as a standard copyright, but copying something from someone else is plain stealing, so don't do that.

Disclaimer: I'm not a legal expert, just my $0.001. But I don't think I'm far off.

Jeroen
I was dreaming of guitarnotes that would irritate an executive kind of guy (FZ)