UError

UError is the error-reporting mechanism used by the ICU library, and is commonly referred to by the type name UErrorCode in the API. The UErrorCode type is defined as a 32-bit integer used to communicate success or failure from ICU functions across modules such as text boundaries, collation, transliteration, and data loading.

In ICU usage, starting status variables are initialized to U_ZERO_ERROR, which represents no error. As operations proceed, functions may return or modify the status to a non-zero value to indicate an error. The status can be tested with macros such as U_SUCCESS or U_FAILURE, where U_SUCCESS means no error, and U_FAILURE indicates an error has occurred. Helpers like u_errorName(UErrorCode code) convert a status code to a human-readable string for reporting.

Common UErrorCode values include U_ZERO_ERROR, U_ILLEGAL_ARGUMENT_ERROR, U_INDEX_OUTOFBOUNDS_ERROR, U_MEMORY_ALLOCATION_ERROR, U_FILE_ACCESS_ERROR, and U_INTERNAL_ERROR, among others. The exact numeric values are implementation-defined but stable within a version of ICU, enabling portable error handling across C and C++ APIs.

Best practices include passing a UErrorCode status by reference to functions that may fail, checking after calls, and returning early if an error is detected. This minimizes cascading failures and simplifies debugging.

See also: ICU, u_errorName, UErrorCode, U_ZERO_ERROR, U_SUCCESS, U_FAILURE.