What does "exclamation mark" mean in programming?

exclamation mark is one of the most common terms in software development. This guide explains what it means, how it is used in practice, and why it matters, with real examples from the developer world.

Definition

The ! character, also called 'bang'. In most languages it is the logical NOT operator (!true is false). In TypeScript, a trailing ! is the non-null assertion operator.

Example

"if (!isLoggedIn) { redirect('/login'); }"

Related terms

operator
boolean

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