Using Patterns to Match Broad Content Types

Problem

You want to classify values into broad categories.

Solution

Use a pattern that is similarly broad.

Discussion

If you need to know whether values are empty or nonempty, or consist only of certain types of characters, the patterns listed in the following table may suffice:

PatternType of value the pattern matches
/^$/ Empty value
/./ Nonempty value
/^s*$/ Whitespace, possibly empty
/^s+$/ Nonempty whitespace
/S/ Nonempty, and not just whitespace
/^d+$/ Digits only, nonempty
/^[a-z]+$/i Alphabetic characters only (case-insensitive), nonempty
/^w+$/ Alphanumeric or underscore characters only, nonempty
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