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Figure A-5

The pattern

rr

indicates to the regular expression engine that an attempt should be made to match the

lowercase alphabetic character

r

; then, if that first match is successful, an attempt should be made to

match the next character. The entire match is successful if the second character is also a lowercase

r

.

If the attempt to match the first character fails, the next character is tested to see if it is a lowercase

r

. If it

is not a lowercase

r

, the match fails, and a new attempt is made to match the following character against

the first

r

of the regular expression pattern.

You can also try this out in the Komodo Regular Expression Toolkit, as shown in Figure A-6, which matches

successive lowercase

m

s. You can download the latest trial version of the Komodo IDE, which includes the

Regular Expression Toolkit, from

http://activestate.com/Products/Komodo

. Komodo version 2.5

is used in this appendix. Clear the regular expression and the test text from the Komodo Toolkit. Enter

mammals

in the area for the string to be matched, and type

m

in the area for the regular expression. At that

point, the initial

m

of

mammals

is matched. Then type a second

m

in the area for the regular expression, and

the highlight indicating a match moves to the

mm

in the middle of

mammals

, as you can see in Figure A-6.

318

Appendix A: Simple Regular Expressions

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