# 22. Virtuoso Functions Guide - boolean

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Functions Index

## boolean

Converts its argument to boolean
boolean boolean ( obj any);
Description

The function converts its argument to a boolean as follows:

- A number is true if and only if it is neither zero nor NaN.

- A node-set is true if and only if it is non-empty.

- A string is true if and only if its length is non-zero.

- An object of a type other than the four basic types is converted to a boolean in a way that is dependent on that type.

Parameters
obj – The object to be converted into boolean.
Return Types

Boolean

Examples

The following expressions are true:

    boolean('aaa') = true()
    boolean('false') = true()
    boolean(false()) = false()
    boolean(.) = true()
    boolean('0') = true()
    boolean(0) = false()

See Also

string() number()