XML in a Nutshell, 3rd Edition

String Functions

XPath includes functions for basic string operations such as finding the length of a string or changing letters from upper- to lowercase. It doesn’t have the full power of the string libraries in Python or Perl—for instance, there’s no regular expression support—but it’s sufficient for many simple manipulations you need for XSLT or XPointer.

The string( ) function converts an argument of any type to a string in a reasonable fashion. Booleans are converted to the string “true” or the string “false.” Node-sets are converted to the string value of the first node in the set. This is the same value calculated by the xsl:value-of element. That is, the string value of the element is the complete text of the element after all entity references are resolved and tags, comments, and processing instructions have been stripped out. Numbers are converted to strings in the format used by most programming languages, such as “1987,” “299792500,” or “2.71828.”

Tip

In XSLT, the xsl:decimal-format element and format-number( ) function provide more precise control over formatting so you can insert separators between groups, change the decimal separator, use non-European digits, and make similar adjustments.

The normal use of most of the rest of the string functions is to manipulate or address the text content of XML elements or attributes. For instance, if date attributes were given in the format MM/DD/YYYY, then the string functions would allow you to target the month, day, and ...