atom_length(+Atom, -Length)

Atom

Atom.

Length

Integer or variable.

Description

Note that (like all predicates that return a number as their last argument), this predicate can be used as a function inside arithmetic expressions.

Modes and Determinism

• atom_length(+, -) is det

Exceptions

(4) instantiation fault

Atom is not instantiated (non-coroutine mode only).

(5) type error

Atom is instantiated, but not to an atom.

(5) type error

Length is neither an integer nor a variable.

Examples

Success:
      atom_length(test, 4).
      atom_length(test,L).         (gives L = 4).
      atom_length(as, X).          (gives X = 2).
      atom_length('4', 1).

Fail:
      atom_length(test, 5).

Error:
      atom_length(Atom, 2).        (Error 4).
      atom_length(Atom, 2.0).      (Error 5).
      atom_length(4, 1).           (Error 5).
      atom_length(as, 2.0).        (Error 5).

See Also