Is there a function which instantly tells you whether an element is part of a list?

I have a very long list of numbers and I want to check whether there's a function (something that would look like PartOfQ[element,list]) that tells you immediately with a True or False as to whether the element in question is part of the list or not.

Ideally it would also tell you its index.

If there isn't a built-in such function, is there an efficient way of building such a function myself?

Answer

Yes. You are looking for MemberQ.

Position will tell you the indexes of all occurrences of the element.

Comments

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