The header <stdlib.h> declares four types and several functions of general utility, and defines several macros.
The types declared are size_t and wchar_t (both described in the ANSI specification refsection 7.1.6),
div_t
which is a structure type that is the type of the value returned by the div function, and
ldiv_t
which is a structure type that is the type of the value returned by the ldiv function.
The macros defined are NULL (described in in the ANSI specification refsection 7.1.6),
EXIT_FAILURE
and
EXIT_SUCCESS, which expand to integral expressions that may be used as the argument to the exit function to return unsuccessful or successful termination status respectively, to the host environment,
RAND_MAX which expands to an integral constant expression, the value of which is the maximum value returned by the rand function, and
MB_CUR_MAX which expands to a positive integer expression whose value is the maximum number of bytes in a multi-byte character for the extended character set specified by the current locale (category LC_TYPE), and whose value is never greater than MB_LEN_MAX