ERANGE

ERANGE is a macro defined in the C standard library header errno.h. It represents a numerical range error and is used as an error code to indicate that a computation or result lies outside the representable range for the given data type. The exact numeric value of ERANGE is implementation-defined; on many systems it is 34, but portable code should not rely on the specific number.

In practice, ERANGE is used by functions that report errors via errno. When a library function encounters a situation where a result cannot be represented within the target type—such as overflow or, in some cases, underflow—it may set errno to ERANGE and return a value that signals the problem (for example, a large positive value, infinity, or a special sentinel). However, not all functions set errno, and the exact conditions under which ERANGE is applied are implementation-dependent.

Relation to other error codes is important: ERANGE denotes a range-related problem, while EDOM denotes a domain error (the input value is not within the function’s valid domain). Both are part of the broader errno mechanism used for error reporting in C libraries and POSIX systems.

Portability and usage: programs that rely on errno to detect errors should include errno.h and check errno after a function signals an error. Because the meaning and set of errno values can vary between libraries, errno should be interpreted in the context of the specific implementation’s documentation. See also errno, EDOM, and EINVAL for related error reporting concepts.