Regex: Matching 4-Digits within words

Question

I have a body of text I'm looking to pull repeat sets of 4-digit numbers out from.

For Example:

The first is 1234 2) The Second is 2098 3) The Third is 3213

Now I know i'm able to get the first set of digits out by simply using:

    /\d{4}/

...returning 1234

But how do I match the second set of digits, or the third, and so on...?

edit: How do i return 2098, or 3213

Answer 1

You don't appear to have a proper answer to your question yet.

The solution is to use the /g modifier on your regex. In list context it will find all of the numbers in your string at once, like this

my $str = 'The first is 1234 2) The Second is 2098 3) The Third is 3213';

my @numbers = $str =~ /\b \d{4} \b/gx;

print "@numbers\n";

output

1234 2098 3213

Or you can iterate through them, using scalar context in a while loop, like this

while ($str =~ /\b (\d{4}) \b/gx) {
  my $number = $1;
  print $number, "\n";
}

output

1234
2098
3213

I have added the \b patterns to the regex so that it only matches whole four-digit numbers and doesn't, for example, find 1234 in 1234567. The /x modifier just allows me to add spaces so that the pattern is more intelligible.