# xf:upper-case

Converts all the lowercase characters of $string-var to their uppercase form.

If the value of $string-var is the empty sequence, the empty sequence is returned. The empty sequence is a sequence containing zero items (), which is similar to null in SQL.

### Signatures

xf:upper-case(xs:string? $string-var) —> xs:string?

### Arguments

Data Type | Argument | Description
--- | --- | ---
xs:string? | $string-var | Represents the string to convert.

### Returns

Returns the $string-var source string converted to uppercase characters.

### Examples

#### Simple

Invoking upper-case("cat") returns the string CAT as shown in the following example query:

    <result>{xf:upper-case("cat")}</result>

The preceding query generates the following result:

    <result>CAT</result>

#### Pass in Null

Invoking upper-case(()) returns the null string as shown in the following example query:

    <result>{xf:upper-case(())}</result>

Note: The string: () is the empty sequence (similar to a SQL null) which is a sequence containing zero items.

The preceding query generates the following result:

    <result/>

Related Topics

W3C upper-case function description.