Strerrorerrno

Strerrorerrno is a function name used in some C libraries and codebases for converting a numeric errno value into a human-readable error message. It serves a role similar to strerror, but takes the error number as an argument rather than using the global errno variable. This can be useful when reporting errors after a function that may modify errno or when translating error codes stored independently of the current errno state.

Because strerrorerrno is not part of the C standard or POSIX, its existence and exact semantics vary by implementation. Some libraries implement it as a simple wrapper around strerror or strerror_r, returning a pointer to a string describing the error, which may come from a static buffer or a thread-local buffer. In some cases, the function may allocate memory or require the caller to manage lifetime. The thread-safety and performance characteristics depend on the specific library and implementation.

Portability and caveats: Because it is non-standard, code using strerrorerrno may not compile or behave identically on all systems. If portability is a concern, strerror_r or custom wrappers using strerror are preferred. When relying on a particular behavior (such as a stable buffer or thread-local storage), that behavior should be documented for the target platform or library.

See also: strerror, strerror_r, errno, errno.h, perror.