boolean

Casts an object to a boolean.

Syntax

• boolean(X)

  • X is any object

Description

If X is any object, boolean(X) is a boolean with a value that depends on X, according to the following rules:

• If X is a number, then boolean(X) is true iff X is not (exactly) zero.

• If X is a string, then:

  • If X converted to lower case is "true", then boolean(X) is true.

  • If X converted to lower case is "false", then boolean(X) is false.

  • Otherwise, an error is raised.

• If X is a container which is not a string, then boolean(X) is true iff #X > 0.

• If X is a null object, then boolean(X) is false.

• If X is a success indication, then boolean(X) is true.

• If X is a boolean, then boolean(X) is X.

• If X is a binary data object, then boolean(X) is true iff X contains at least one non-zero byte.

• If none of the above points apply, then boolean(X) is true.

See also

• IsBoolean

• Type conversion functions (list)