fn:exists
Whether an argument is the empty sequence
Description
The fn:exists function returns true if the sequence contains one or more items; it is the opposite of the fn:empty function. It is often unnecessary to call the fn:exists function because sequences are automatically converted to the effective boolean value where a boolean value is expected.
This description is © Copyright 2007, Priscilla Walmsley. It is excerpted from the book XQuery by Priscilla Walmsley, O'Reilly, 2007. For a complete explanation of this function, please refer to Appendix A of the book.
Arguments and Return Type
| Name | Type |
|---|---|
$arg |
item()* |
| return value | xs:boolean |
Examples
| XQuery Example | Results |
|---|---|
exists( ('a', 'b', 'c') ) |
true |
exists( '' ) |
true |
exists( () ) |
false |
exists( false() ) |
true |
See Also
| fn:empty | Whether a value is the empty sequence |
| fn:boolean | The effective boolean value of a sequence |
History
| Published On | Last Updated | Contributor(s) |
|---|---|---|
| 2006-06-27 | 2007-02-26 | W3C, XQuery 1.0 and XPath 2.0 Functions and Operators, http://www.w3.org/TR/xpath-functions/ |
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