matchChunk

Typefunction
DictionaryLCS
LibraryLiveCode Script
Syntax
matchChunk(<string>, <regularExpression> [, <positionVarsList>])
Summary

Returns true if a regular expression is found in the specified string, false otherwise.

Introduced1.0
Changes

The regular expression format changed in version 2.0 to use PCRE compatible syntax.

OSmac, windows, linux, ios, android
Platformsdesktop, server, mobile
Parameters
NameTypeDescription
string
regularExpression

Any expression that evaluates to a regular expression.

positionVarsList

The optional positionVarsList consists of an even number of existing variables, separated by commas.

Example
matchChunk("Hello","Hel") -- returns true
matchChunk("Hello","o$") -- also returns true
matchChunk(the short name of this stack,"^rev") -- starts with "rev"
matchChunk(field "Title",myExpr,startMatch,endMatch)
Values
NameTypeDescription
return

The matchChunk function returns true or false.

RelatedProperty: caseSensitive
Control Structure: function
Keyword: string, character
Constant: return
Function: matchText, value
Command: put, filter
Glossary: property, return, variable, value, call, regular expression, case-sensitive, case-insensitive, function, command
Description

Use the matchChunk function to check whether a string contains a specified pattern.

If the regularExpression includes a pair of parentheses, the position of the substring matching the part of the regular expression inside the parentheses is placed in the variables in the positionVarsList. The number of the first character in the matching substring is placed in the first variable in the positionVarsList, and the number of the last character is placed in the second variable. Additional starting and ending positions, matching additional parenthetical expressions, are placed in additional pairs of variables in the positionVarsList. If the matchChunk function returns false, the values of the variables in the positionVarsList are not changed.

The string and regularExpression are always case-sensitive, regardless of the setting of the caseSensitive property. (If you need to make a case-insensitive comparison, use "(?i)" at the start of the regularExpression to make the match case-insensitive.)

Important: Variables in the positionVarsList must be created before the matchChunk function is called. The matchChunk function, unlike the put command, does not create them automatically.

The matchChunk and matchText functions return the same value, given the same string and regularExpression. The difference between the two is that the matchChunk function records the positions of matched substrings in the optional positionVarsList variables, while the matchText function records the substrings themselves.

Tip: LiveCode implements regular expressions compatible with the PCRE library. For detailed information about regular expression elements you can use with this function, see the PCRE pattern documentation at http://www.pcre.org/original/doc/html/pcrepattern.html.