Elvis operator

In certain computer programming languages, the Elvis operator, often written ?:, is a binary operator that returns its first operand if that operand evaluates to a true value, and otherwise evaluates and returns its second operand. This is identical to a short-circuit or with "last value" semantics. The notation of the Elvis operator was inspired by the ternary conditional operator, ? :, since the Elvis operator expression A ?: B is approximately equivalent to the ternary conditional A ? A : B.

This article is about the use of a ?: operator as a binary operator. For use as a ternary operator, see ?:.

The name "Elvis operator" refers to the fact that when its common notation, ?:, is viewed sideways, it resembles an emoticon of Elvis Presley with his signature hairstyle.

A similar operator is the null coalescing operator, where the boolean truth check is replaced with a check for non-null instead. This is usually written ??, and can be seen in languages like C#.

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