Select a certain part of this string

Question

I need to select a small portion of a string.

Here's an example string: http://itunes.apple.com/app/eyelashes/id564783832?uo=5

I need: 564783832

A couple of things to keep in mind:

• The number will always be preceded by id (ie. id564783832)
• There may or may not be a ?uo=5 following the number (and it could be other parameters besides uo)
• The string I need can be different lengths (won't always be 9 digits)
• The text preceding id will have similar formatting (same # of slashes, but text will be different)

This will ultimately be implemented with Ruby.

Answer 1

Here's mine:

[\w\/]+id(\d+)(\?|$)

Answer 2

You can match some sequence of digits preceded by "id" - this assumes that those are the only sequence of digits preceded by "id":

(?<=id)\d++

A test case in Java:

public static void main(String[] args) {
    String input = "http://itunes.apple.com/app/eyelashes/id564783832?uo=5";
    Pattern pattern = Pattern.compile("(?<=id)\\d++");
    Matcher matcher = pattern.matcher(input);
    while (matcher.find()) {
        System.out.println(matcher.group());
    }
}

Output

564783832

Answer 3

without knowing your language/tool, just assume look behind was supported.

'(?<=id)\d+'

Answer 4

With awk

awk '{print $2}' FS='(id|?)'