If you have doubts about a particular snippet, you can send a message to its author.

By far and large, most code posted here is too small to be covered by Copyright. They cover basic tasks and module usage, and thus cover necessary steps for doing those tasks or using those modules. That's not Copyrightable.

And then there's intent. Except for questions and CUFP, the code posted here is given to help the requester and other readers.

Feel free to use any of mine in any manner you wish.

This subject has come up before. You should do a search for previous discussions on the topic.