XPATH has a rich set of functions that can be used to evaluate, manipulate and otherwise traverse an XML document.
XPATH functions are grouped by and return one of the following four types:
- Boolean
- String
- Number
- Node-Set
XAPTH functions are NOT strongly typed; the XPATH processor will attempt to do the necessary translations where appropriate and where it can. The function will fail if the XPATH processor is unable to do the translation. In such cases the function will return the default value or indicate an error condition, eg. NaN.
XPATH Functions: Boolean
Boolean functions return values of type boolean – that is either true or false.
| Functions | Description |
| true() | returns true |
| false() | returns false |
| not() | takes a boolean argument and returns the inverse value. |
| boolean() | Takes an argument and converts it into a boolean value.
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XPATH Functions: String
XPATH String functions are typically used to manipulate text values:
| Functions | Description |
| substring-before(s1, s2) | Returns the substring of s1 that precedes the first occurrence of s2 . |
| substring-after(s1, s2) | Returns the substring of s1 that follows the first occurrence of s2 . |
| translate(s1, s2, sr) | Looks in s1 for any characters in s2 and replaces them with characters in s3 . |
| string-length(s) | Returns the number of characters in the argument s. |
| substring(s, index, [length]) | Returns the substring of s starting at index, continuing for length characters . |
| starts-with(s1, s2) | Returns true if s1 starts with s2; otherwise returns false. |
| contains(s1, s2) | Returns true if s2 is a substring of s1; otherwise returns false. |
XPATH Functions: Number
XPATH provides some simple numeric functions:
| Functions | Description |
| number() | Returns the numeric value of the argument |
| abs() | Returns the absolute value of the argument |
| floor() | Returns the smallest integer that is greater than the number argument |
| ceiling() | Returns the largest integer that is not greater than the number argument |
| round() | Rounds the number argument to the nearest integer |
| round-half-to-even() | |
| sum() | Adds up the parameters passed in and returns a sum |
XPATH Functions: Node-Set
| Functions | Description |
| count() | Returns the number of nodes in a node-set. |
| position() | Returns a number equal to the current position of a node in the node-set; i.o.w. returns the index value of the node. |