Sentinel Value

Definitions

1. A special in-band value (such as -1, null, or EOF) used to signal an exceptional condition or the end of data within a stream or return type, avoiding the need for a separate error channel — though prone to ambiguity if the sentinel could also be a legitimate value.

   In plain English: A magic value like -1 or null that means 'not found' or 'end of data' instead of being an actual result.

   Example: "indexOf returns -1 as a sentinel value when the substring isn't found, which is why you see the classic `if (idx !== -1)` check everywhere."

Related Terms

• C Backend
• Error Union
• Exception
• GLib
• GObject
• Header File
• Recover
• Panic