In traditional string matching, as used by the ColdFusion Find and Replace functions, you provide the string pattern to search for and the string to search. The following example searches a string for the pattern " BIG " and returns a string index if found. The string index is the location in the search string where the string pattern begins.
<cfset IndexOfOccurrence=Find(" BIG ", "Some BIG string")>
<!--- The value of IndexOfOccurrence is 5 --->
You must provide the exact string pattern to match. If the exact pattern is not found, Find returns an index of 0. Because you must specify the exact string pattern to match, matches for dynamic data can be very difficult, if not impossible, to construct.
The next example uses a regular expression to perform the same search. This example searches for the first occurrence in the search string of any string pattern that consists entirely of uppercase letters enclosed by spaces:
<cfset IndexOfOccurrence=REFind(" [A-Z]+ ", "Some BIG string")>
<!--- The value of IndexOfOccurrence is 5 --->
The regular expression " [A-Z]+ " matches any string pattern consisting of a leading space, followed by any number of uppercase letters, followed by a trailing space. Therefore, this regular expression matches the string " BIG " and any string of uppercase letters enclosed in spaces.
By default, the matching of regular expressions is case-sensitive. You can use the case-insensitive functions, REFindNoCase and REReplaceNoCase, for case-insensitive matching.
Because you often process large amounts of dynamic textual data, regular expressions are invaluable in writing complex ColdFusion applications.