Strings can be concatenated together using one of two functions: concat or string-join. XQuery does not allow use of concat operators such as +, &, or || to concatenate strings. The concat function accepts individual string arguments and concatenates them together. This function is unique in that it accepts a variable number of arguments. For example:

concat("a", "b", "c")

returns the string abc. The string-join function, on the other hand, accepts a sequence of strings. For example:

string-join( ("a", "b", "c"), "")

also returns the string abc. In addition, string-join allows a separator to be passed as the second argument. For example:

string-join( ("a", "b", "c"), "/")

returns the string a/b/c.

Strings can be split apart, or tokenized, using the tokenize function. This function breaks a string into a sequence of strings, using a regular expression to designate the separator character(s). For example:

tokenize("a/b/c", "/")

returns a sequence of three strings: a, b, and c. Regular expressions such as s, which represents a whitespace character (space, line feed, carriage return, or tab), and W, which represents a nonword character (anything other than a letter or digit) are often used with this function. A list of useful regular expressions for tokenization can be found in Appendix A in the discussion of the tokenize function. Table 17-7 shows some examples of the tokenize function.

Strings can be constructed from a sequence of Unicode code-point values (expressed as integers) using the codepoints-to-string function. For example:

codepoints-to-string((97, 98, 99))

returns the string abc. The string-to-codepoints function performs the opposite; it converts a string to a sequence of code points. For example:

string-to-codepoints("abc")

returns a sequence of three integers 97, 98, and 99.