python - Regex to match digits of specific length

Question

I am looking to match a 15 digit number (as part of a larger regex string). Right now, I have

ddddddddddddddd

but I feel like there must be a cleaner way to do this.

Answer 1

You can generally do ranges as follows:

d{4,7}

which means a minimum of 4 and maximum of 7 digits. For your particular case, you can use the one-argument variant, d{15}.

Both of these forms are supported in Python's regular expressions - look for the text {m,n} at that link.

And keep in mind that d{15} will match fifteen digits anywhere in the line, including a 400-digit number. If you want to ensure it only has the fifteen, you use something like:

^d{15}$

which uses the start and end anchors, or

^D*d{15}D*$

which allows arbitrary non-digits on either side.