Lesson 10
Embedding Conditions
A powerful yet infrequently used feature of the regular expression language is the capability to embed conditional processing within an expression. This lesson will explore this topic.
Why Embed Conditions?
(123)456-7890 and 123-456-7890 are both acceptable presentation formats for North American phone numbers. 1234567890, (123)-456-7890, and (123-456-7890 all contain the correct number of digits, but are badly formatted. How could you write a regular expression to match only the acceptable formats and not any others?
This is not a trivial problem; consider this obvious solution:
Text
123-456-7890 (123)456-7890 (123)-456-7890 (123-456-7890 1234567890 123 456 7890
RegEx
\(?\d{3}\)?-?\d{3}-\d ...Get Learning Regular Expressions, First Edition now with the O’Reilly learning platform.
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