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Searches for a regular expression in the input string beginning at the offset you enter and, if it finds a match, splits the string into three substrings and any number of submatches. Resize the function to view any submatches found in the string.

The Match Regular Expression function gives you more options for matching strings but performs more slowly than the Match Pattern function.

For components utilizing the PCRE library package, the following copyright notice applies.

Regular expression support is provided by the PCRE library package, which is open source software, written by Philip Hazel, and copyright by the University of Cambridge, England.

Details  

Block Diagram Inputs

Block Diagram Outputs

Block Diagram Inputs

Parameter	Description
multiline?	Sets whether or not to treat the text in input string as a multiple-line string. This affects how the ^ and $ characters handle matches. When FALSE (the default), entering "^" matches the beginning of the line in input string only and entering "$" matches the end of input string only. When TRUE, "^" matches the beginning of any line in input string and "$" matches the end of any line in input string.
ignore case?	Specifies whether the string search is case sensitive. If FALSE (default), the string search is case sensitive.
input string	Specifies the input string the function searches. This string cannot contain null characters.
regular expression	Specifies the pattern you want to search for in input string. If the function does not find a match, whole match and after match contain empty strings, before match contains the entire input string, offset past match returns –1, and all submatches outputs return empty strings. Place any substrings you want to search for in parentheses. The function returns any substring expressions it finds in substring 1..n. This string cannot contain null characters.
offset	Determines the number of characters into input string at which the function starts searching for search string.
error in	Describes error conditions that occur before this VI or function runs. The default is no error. If an error occurred before this VI or function runs, the VI or function passes the error in value to error out. This VI or function runs normally only if no error occurred before this VI or function runs. If an error occurs while this VI or function runs, it runs normally and sets its own error status in error out. Use the Simple Error Handler or General Error Handler VIs to display the description of the error code. Use error in and error out to check errors and to specify execution order by wiring error out from one node to error in of the next node.

Block Diagram Outputs

Parameter	Description
before match	Returns a string containing all the characters before the match.
whole match	Contains all the characters that match the expression entered in regular expression. Any substring matches the function finds appear in the submatch outputs.
after match	Contains all characters following the matched pattern entered in regular expression.
offset past match	Returns the index in input string of the first character after the last match. If the VI does not find a match, offset past match is –1.
error out	Contains error information. If error in indicates that an error occurred before this VI or function ran, error out contains the same error information. Otherwise, it describes the error status that this VI or function produces.

Match Regular Expression Details

Note  Match Regular Expression does not support null characters in strings.

Use regular expressions in this function to refine searches.

Certain regular expressions that use alternation (such as (.|\s)*) require significant resources to process when applied to large input strings. In some cases a stack overflow will occur and you will get an error dialog. If this occurs try to simplify your regular expression, or reduce the size of the string that you are parsing.

The following table shows examples of regular expressions you can use with this function. Some of these examples use special characters to refine the search.

Characters to Find	Regular Expression
VOLTS	VOLTS
All uppercase and lowercase versions of volts, that is, VOLTS, Volts, volts, and so on	[Vv][Oo][Ll][Tt][Ss]
A space, a plus sign, or a minus sign	[+-]
A sequence of one or more digits	[0-9]+
Zero or more spaces	\s* or * (that is, a space followed by an asterisk)
One or more spaces, tabs, new lines, or carriage returns	[\t \r \n \s]+
One or more characters other than digits	[~0-9]+
The word Level only if it begins at the offset position in the string	^Level
The word Volts only if it appears at the end of the string	Volts$
The longest string within parentheses	(.*)
The longest string within parentheses but not containing any parentheses within it	([~()]*)
A left bracket	\[
A right bracket	\]
cat, dog, cot, dot, cog, and so on.	[cd][ao][tg]