Examples of Screening Rules

This section provides examples of screening rules.

Credit Card Number

To find text that includes a typical credit card number, you need to match a sequence of four groups of four digits, each group separated by -(hyphen):

\d\d\d\d\-\d\d\d\d\-\d\d\d\d\-\d\d\d\d

Important

This regular expression also works without the \ (backslash) before the hyphens. However, it is better practice to write \- for the character hyphen, because the hyphen also has a special use in range expressions like [a-z].

Or if you want to allow for the possibility that some people will omit the hyphens, use? to make the hyphen optional:

\d\d\d\d\-?\d\d\d\d\-?\d\d\d\d\-?\d\d\d\d

You could also use the repetition notation to shorten each \d\d\d\d to \d{4}.

North American Phone Number

North American phone numbers consists of ten digits, grouped into two groups of three and one of four. There are a number of ways for the groups to be separated:

203-555-1234

(203) 555-1234

(203)555-1234

203 555-1234

203.555.1234

The following regular expression matches all of the above:

(\d\d\d|\(\d\d\d\))[\s\.\-]?\s*\d\d\d[\-\.]\d\d\d\d

The table "Phone Number Regular Expression" analyzes this regular expression.

Phone Number Regular Expression

Symbols	Meaning	Remarks
\d\d\d	Three digits
\d\d\d|\(\d\d\d\)	Three digits, or three digits enclosed in parentheses	\ turns off the special meaning of the character (
[\s\.\-]?	Space or period or hyphen or zero	Any one of the items enclosed in square brackets, either once or not at all
\s*	Zero or more spaces
\d\d\d	Three digits
[\-\.]	Hyphen or period	Note again the need to use \
\d\d\d\d	Four digits

Telltale Words

To screen for interactions from dissatisfied customers, you might try a regular expression like the following:

(not\s([a-z]+\s)*(pleased | satisfied)) | unhappy | complain

The first part of this expression matches not followed by zero or more words followed by pleased or satisfied; for example, not very pleased, not satisfied, not at all satisfied (but it also matches strings like can not believe how pleased I am). The rest matches the single words "unhappy" and "complain."