PHP PREG_SPLIT on numbers 1-100

Question

I am working on some code to break down the full text of a test that will copied and pasted with the following format:

1. This is question number one.
A. Answer 1 
B. Answer 2
C. Answer 3
D. Answer 4
2. This is question number two.
3. This is another question, number three.

45. Ken has uses his money, $353. How much does he have after spending $214.

I am using the following preg_split:

$questions = preg_split("/[0-9]+\./", $_POST[test]);

My problem has come in with questions like #45 where there are numbers in the question itself and they are followed by a period.

I just want to match the numbers 1-100 followed by a period. Eg.

1. 2. 3. 4. 5. etc

Answer 1

I think it is better to use multiline flag with ^:

$questions = preg_split('/^ *[0-9]+\. +/m', $_POST[test]);

Answer 2

A number between 1 and 100, followed by a period, can be matched by

/\b(?:100|[1-9][0-9]?)\./

but if the actual rule is to match a number at the start of a line, use

/^\d+\./m

Answer 3

You can use preg_match_all() instead:

preg_match_all('~(?:^|\R)[0-9]+\. \K.+~', $_POST['test'], $matches);
$questions = $matches[0];

Answer 4

Use ^ to specify that it's the beginning of the line, using the g and m modifiers to specify global and multiline:

/^[0-9]+\.\s/m