What does "null pointer exception" mean in programming?
null pointer exception 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
An error that occurs when code tries to use a reference that points to nothing (null or undefined). One of the most common runtime errors across all languages. Tony Hoare, who invented null, called it his 'billion-dollar mistake'. Modern languages like Kotlin, Rust, and Swift use type systems to prevent it.
Example
"We got a null pointer exception because user.address was null — we forgot to check before accessing user.address.city."
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