What regex would detect if a string is part of a numbered list?

Question

I am really struggling to find a regular expression that will reliably check to see if a string is part of a numbered list (such as those you would find in a common word-processor)

Therefore, I would like it to return true if the beginning of the string is a number followed by a fullstop and a space.

For single or even double digit numbers I can of course do this easily without the need for regular expressions, but since the number could be any size, it will not work.

Example 1

"1. This is a string"

Should return true because the string begins with: "1. "

Example 2

"3245. This is another string"

Should return true because the string begins with: "3245. "

Example 3

"This is a 24. string"

Should return false

Because there is no pattern matched at the beginning of the string... however...

Example 4

"3. This is 24. string"

Should still return true

I hope this is clear enough.

Thanks in advance for any help.

Answer 1

It is a pretty simple regex. The following will find the start of the string, then a digit character repeated one or more time, then a period character, then the space character.

^\d+\. 

REY

In JavaScript you can do the following to test the string:

var startsWithNumber = /^\d+\. /m.test('34. this should return true.');

jsFiddle

Answer 2

You could simply do..

/^\d+\.\s+/ or even /^\d*\.\s*/

Explanation of + and * operators

\d         Any digit
\s         Any whitespace character
*          Zero or more
+          One or more