Regex to find a number in a string

Question

I've got a string that may or may not contain a number of 4 or 5 digits. I'm looking for a regex that can detect if the string does in fact have such a number.

Answer 1

Simple \d{4,5} will suffice.

Answer 2

Perhaps

\d{4,5}

?

Answer 3

.NET? Then it's [0-9]{4,5}

Answer 4

\d{4,5} will also find strings with 6 digit numbers in - I don't know whether that's a problem or not. You might want to do something like this:

([^\d]+|^)\d{4,5}[^\d]

Answer 5

The foolproof one to avoid longer numbers would be:

([^\d]|^)\d{4,5}([^\d]|$)

I'm assuming you don't want to allow for a comma after the thousands digit? If you do then:

([^\d]|^)\d{1,2},\d{3}([^\d]|$)