User Guide

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Returning matched subexpressions 153

This example returns "Hello Mr. Bond". If you did not prohibit the capturing of the Hi/Hello

group, the \2 backreference would end up referring to that group instead of " Bond", and the

result would be "Hello Mr.ello".

Returning matched subexpressions

The REFind and REFindNoCase functions return the location in the search string of the first

match of the regular expression. Even though the search string in the next example contains two

matches of the regular expression, the function only returns the index of the first:

To find all instances of the regular expression, you must call the REFind and REFindNoCase

functions multiple times.

Both the

REFind and REFindNoCase functions take an optional third parameter that specifies the

starting index in the search string for the search. By default, the starting location is index 1, the

beginning of the string.

To find the second instance of the regular expression in this example, you call

REFind with a

starting index of 8:

In this case, the function returns an index of 9, the starting index of the second string " BIG ".

To find the second occurrence of the string, you must know that the first string occurred at index

5 and that the string’s length was 5. However,

REFind only returns starting index of the string,

not its length. So, you either must know the length of the matched string to call

REFind the

second time, or you must use subexpressions in the regular expression.

The

REFind and REFindNoCase functions let you get information about matched subexpressions.

If you set these functions’ fourth parameter,

ReturnSubExpression, to True, the functions

return a CFML structure with two arrays,

pos and len, containing the positions and lengths of

text strings that match the subexpressions of a regular expression, as the following example shows:

</cfoutput><br>

The following figure shows the output of the cfdump tag: