string_length(+String, -Length)

String

String.

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

• string_length(+, -) is det

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