Regex::Split Method (String, String)
Splits an input string into an array of substrings at the positions defined by a regular expression pattern.
Assemblies: System.Text.RegularExpressions (in System.Text.RegularExpressions.dll)
System (in System.dll)
The Regex::Split methods are similar to the String::Split method, except that Regex::Split splits the string at a delimiter determined by a regular expression instead of a set of characters. The input string is split as many times as possible. If pattern is not found in the input string, the return value contains one element whose value is the original input string.
The pattern parameter consists of regular expression language elements that symbolically describe the string to match. For more information about regular expressions, see .NET Framework Regular Expressions and Regular Expression Language - Quick Reference.
If multiple matches are adjacent to one another, an empty string is inserted into the array. For example, splitting a string on a single hyphen causes the returned array to include an empty string in the position where two adjacent hyphens are found, as the following code shows.
If a match is found at the beginning or the end of the input string, an empty string is included at the beginning or the end of the returned array. The following example uses the regular expression pattern \d+ to split an input string on numeric characters. Because the string begins and ends with matching numeric characters, the value of the first and last element of the returned array is String::Empty.
If capturing parentheses are used in a Regex::Split expression, any captured text is included in the resulting string array. For example, if you split the string "plum-pear" on a hyphen placed within capturing parentheses, the returned array includes a string element that contains the hyphen.
However, when the regular expression pattern includes multiple sets of capturing parentheses, the behavior of this method depends on the version of the .NET Framework. In the .NET Framework 1.0 and 1.1, if a match is not found within the first set of capturing parentheses, captured text from additional capturing parentheses is not included in the returned array. Starting with the .NET Framework 2.0, all captured text is also added to the returned array. For example, the following code uses two sets of capturing parentheses to extract the elements of a date, including the date delimiters, from a date string. The first set of capturing parentheses captures the hyphen, and the second set captures the forward slash. If the example code is compiled and run under the .NET Framework 1.0 or 1.1, it excludes the slash characters; if it is compiled and run under the .NET Framework 2.0 or later versions, it includes them.
If the regular expression can match the empty string, Split will split the string into an array of single-character strings because the empty string delimiter can be found at every location. For example:
Note that the returned array also includes an empty string at the beginning and end of the array.
The RegexMatchTimeoutException exception is thrown if the execution time of the split operation exceeds the time-out interval specified for the application domain in which the method is called. If no time-out is defined in the application domain's properties, or if the time-out value is Regex::InfiniteMatchTimeout, no exception is thrown.Notes to Callers
This method times out after an interval that is equal to the default time-out value of the application domain in which the method is called. If a time-out value has not been defined for the application domain, the value InfiniteMatchTimeout, which prevents the method from timing out, is used. The recommended static method for splitting text on a pattern match is Regex::Split(String, String, RegexOptions, TimeSpan), which lets you set the time-out interval.