errorCode

Error code is a symbolic numeric or alphanumeric identifier returned by software to indicate success, failure, or other status. In programming and computing, error codes provide a compact, language-agnostic mechanism for reporting outcomes from functions, system calls, and protocols. They allow callers to decide how to react without parsing human-readable messages.

Common families of error codes include POSIX errno values (for example ENOENT 2, EACCES 13), Windows HRESULTs (for example S_OK 0x00000000, E_FAIL 0x80004005), and HTTP status codes (200 OK, 404 Not Found, 500 Internal Server Error). Many APIs return numeric codes with optional textual messages, and these codes may be propagated across process boundaries or network calls.

Error codes are used for diagnostics, control flow, and user messaging. They enable programs to distinguish among different failure modes, trigger retries or fallbacks, and log reproducible signals for debugging. In multi-layer systems, codes are often mapped to higher-level descriptions while preserving the original code for developers and supporting localization for users.

Design considerations emphasize standardization and stability. When possible, use established code sets to reduce ambiguity, keep the numeric domain stable across releases, and provide clear, localized messages that do not reveal sensitive internals. Codes should be propagated consistently across interfaces and accompanied by contextual information in logs to aid diagnosis.

See also: error handling, exception handling, exit code, status code, standardized error codes.