Preg Match Empty String

regex preg-match
Denis Pshenov picture Denis Pshenov · Nov 27, 2009 · Viewed 45.6k times · Source

How to preg_match for an null (empty) string??

I need something like:

/([0-9]|[NULL STRING])/

Answer

Mikael Auno picture Mikael Auno · Nov 27, 2009

You can use ^ to match beginning-of-line, and $ to match end-of-line, thus the regular expression ^$ would match an empty line/string.

Your specific example (a line/string containing a single digit or being empty) would easiest be achieved with ^[0-9]?$.

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