NOTFOUNDreturn

NOTFOUNDreturn is a naming convention used in software development to denote a sentinel value or special return that indicates a failed lookup or missing item. It is used to signal that a requested element could not be located without throwing an exception or returning a data object.

In practice, a function that searches a collection might return NOTFOUNDreturn when the desired element cannot be found. The actual value used as NOTFOUNDreturn varies by language and library; common forms include -1 in index-based searches, null or None in languages with a null value, or a dedicated sentinel object or error code. The exact choice depends on the surrounding type system and error-handling strategy.

Contexts where NOTFOUNDreturn appears include file systems, databases, configuration lookups, resource retrieval, and API endpoints. It often serves to keep control flow simple in tight loops or performance-critical paths, where exceptions would be too costly or cumbersome.

Design and interoperability: Some APIs standardize NOTFOUNDreturn to streamline error handling, often paired with documentation and tests. Others favor exceptions, optional types, or explicit error objects, which can provide clearer semantics and better type safety.

Pros and cons: A sentinel return can make lookup code concise and explicit about failure. However, it risks ambiguity if the sentinel value is not well documented or could appear as valid data. Clear documentation, consistent usage, and consideration of language-specific patterns are important.

Related concepts: sentinel value, NotFound, optional (Maybe/Option), NotFoundError.