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string_length(+String, ?Length)

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

Description

The length of the string String is unified with Length.

Fail Conditions

Fails if Length does not unify with the length of String.

Resatisfiable

No.

Exceptions

(4) instantiation fault
String is not instantiated (non-coroutine mode only).
(5) type error
String is instantiated, but not to a string.
(5) type error
Length is neither an integer nor a variable.

Examples

Success:
      string_length("Peter ",X).  (gives X=6).
      string_length("Peter ",6).
      string_length("401.35",6).

Fail:
      string_length("Peter",6).

Error:
      string_length(Str,Len).            (Error 4).
      string_length(Str,6).              (Error 4).
      string_length("small",5.0).        (Error 5).
      string_length(Str,instantiated).   (Error 5).
      string_length(Str,46.2)            (Error 5).
      string_length('this one',L).       (Error 5).

See Also

append_strings / 3, atom_length / 2, concat_strings / 3