Regex to display a string from the second last occurence of a character

Question

Need an Regex to display a string from the second last occurence of a character

Example: "/folder1/folder2/folder3/folder4/"

In this case, if I ask for 2nd occurrence of slash (/) from last , it appears before folder4, and I expect to return substring from 2nd last occurrence of a character.

i.e the return string should be folder4/

[Click for answer](http://docs.oracle.com/javase/7/docs/api/java/lang/String.html). — Maroun, Apr 07 '14 at 06:43
possible duplicate [how-to-find-nth-occurrence-of-character-in-a-string][1] [1]: http://stackoverflow.com/questions/3976616/how-to-find-nth-occurrence-of-character-in-a-string — yarivt, Apr 07 '14 at 06:47

score 2 · Answer 1 · answered Apr 10 '14 at 14:06

2

In php:

$str = "/folder1/folder2/folder3/folder4/";
$str = preg_replace('#^.*/([^/]+/[^/]*)$#', "$1", $str);

In perl:

$str = "/folder1/folder2/folder3/folder4/";
$str =~ s#^.*/([^/]+/[^/]*)$#$1#;

answered Apr 10 '14 at 14:06

Toto

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This was very useful, thanks! For the RAW regex, if anybody else is gonna use this, ignore the hashtags - these are php-specific – lucidbrot Aug 24 '16 at 12:40

ifloop · Accepted Answer · 2014-04-07T06:56:05.047

Look for the last occurence of your token
Take the result - 1 as parameter for a second lastIndexOf()
Take this result as param for substring()

Like so:

final String example = "/folder1/folder2/folder3/folder4/";
final String result  = example.substring(example.lastIndexOf('/', example.lastIndexOf('/') - 1), example.length() - 1);

System.out.printf("%s\n", result);

Or a bit more readable

final String example = "/folder1/folder2/folder3/folder4/";
int pos;

pos = example.lastIndexOf('/');
pos = example.lastIndexOf('/', pos - 1);
result = example.substring(pos, example.length - 1);

System.out.println(result);

exactly the one i need. Thanks for your immediate answer. – Birlla Apr 07 '14 at 09:27 — Birlla, Apr 07 '14 at 09:27

score 0 · Answer 3 · answered Jan 04 '17 at 21:08

in Java:

    String fileName = "/folder1/folder2/folder3/folder4/";
    ArrayList<String> arr = new ArrayList<>();

    Pattern p = Pattern.compile("(.*?)\/");
    Matcher m = p.matcher(fileName);
    while(m.find())
    {
        arr.add(m.group(1));            
    }       
    return arr.get(arr.size()-2);

where 2 is occurrence. This allows you to have everything grouped so you can handle also other groups.

Regex to display a string from the second last occurence of a character

3 Answers3

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