Extract 4-digit year value from a string

Question

I have a year listed in my string

$s = "Acquired by the University in 1988";

In practice, that could be anywhere in this single line string. How do I extract it using regex? I tried \d and that didn't work, it just came up with an error.

I'm using preg_match in LAMP 5.2

Answer 1

/(^|\s)(\d{4})(\s|$)/gm

Matches

Acquired by the University in 1988
The 1945 vintage was superb
1492 columbus sailed the ocean blue

Ignores

There were nearly 10000 people there!
Member ID 45678
Phone Number 951-555-2563