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-1

Universal error/EOF sentinel

category

sentinel

normalized

-1

confirmed

2026-05-24

lookups

1

source

https://en.wikipedia.org/wiki/Sentinel_value

The most common in-band sentinel: returned by C functions for failure (read, write, open), by getchar/fgetc as EOF, and used as a "not found" index in countless APIs. As an unsigned value it becomes all-ones (0xFFFFFFFF).