Testing the type of a term

intPL_term_typeterm_t Obtain the type of a term, which should be a term returned by one of the other interface predicates or passed as an argument. The function returns the type of the Prolog term. The type identifiers are listed below. Note that the extraction functions PL_ge_t*() also validate the type and thus the two sections below are equivalent.

PL_VARIABLE	An unbound variable. The value of term as such is a unique identifier for the variable.
PL_ATOM	A Prolog atom.
PL_STRING	A Prolog string.
PL_INTEGER	A Prolog integer.
PL_FLOAT	A Prolog floating point number.
PL_TERM	A compound term. Note that a list is a compound term 2.

The functions PL_is_type are an alternative to PL_term_type. The test PL_is_variableterm is equivalent to PL_term_typeterm == PL_VARIABLE, but the first is considerably faster. On the other hand, using a switch over PL_term_type is faster and more readable then using an if-then-else using the functions below. All these functions return either TRUE or FALSE.

intPL_is_variableterm_t Returns non-zero if term is a variable. intPL_is_atomterm_t Returns non-zero if term is an atom. intPL_is_stringterm_t Returns non-zero if term is a string. intPL_is_integerterm_t Returns non-zero if term is an integer. intPL_is_floatterm_t Returns non-zero if term is a float. intPL_is_compoundterm_t Returns non-zero if term is a compound term. intPL_is_functorterm_t, functor_t Returns non-zero if term is compound and its functor is functor. This test is equivalent to PL_get_functor, followed by testing the functor, but easier to write and faster. intPL_is_listterm_t Returns non-zero if term is a compound term with functor ./2 or the atom []. intPL_is_atomicterm_t Returns non-zero if term is atomic (not variable or compound). intPL_is_numberterm_t Returns non-zero if term is an integer or float.