[ Strings and Atoms | The ECLiPSe Built-In Predicates | Reference Manual | Alphabetic Index ]

atom_length(+Atom, ?Length)

Succeeds if Length is the length of Atom.
+Atom
Atom.
?Length
Integer or variable.

Description

The length of an atom Atom is unified with Length. The length of an atom is the number of characters in the atom's name.

Fail Conditions

Fails if Length does not unify with the length of the atom Atom.

Resatisfiable

No.

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

atom / 1, atom_string / 2, string_length / 2