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To look for lines that contain matches for

colour

and

color

using the

findstr

utility, enter the following

at the command line:

findstr /N colo*r Colors.txt

The preceding command line assumes that the file

Colors.txt

is in the current directory.

Figure A-15 shows the result from using the

findstr

utility on

Colors.txt

.

Notice that lines that contain the sequences of characters

color

and

colour

are successfully matched,

whether as whole words or parts of longer words. However, notice, too, that the slightly strange “word”

colouuuurful

is also matched due to the

*

metacharacter’s allowing multiple occurrences of the lower-

case letter

u

. In most practical situations, such bizarre “words” won’t be an issue for you, and the

*

quanti-

fier will be an appropriate substitute for the

?

quantifier when using the

findstr

utility. In some situations,

where you want to match precisely zero or one specific characters, the

findstr

utility may not provide

the functionality that you need, because it would also match a character sequence such as

colonifier

.

Figure A-15

Having seen how you can use a single optional character in a regular expression pattern, take a look at

how you can use multiple optional characters in a single regular expression pattern.

Matching Multiple Optional Characters

Many English words have multiple forms. Sometimes, it may be necessary to match all of the forms of

a word. Matching all those forms can require using multiple optional characters in a regular expression

pattern.

Consider the various forms of the word

color

(U.S. English) and

colour

(British English). They include

the following:

color (U.S. English, singular noun)

colour (British English, singular noun)

colors (U.S. English, plural noun)

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Appendix A: Simple Regular Expressions

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