how to grab part of a url string with php

Question

I am using a filemangement system and to protect the url. Manipulation of the url string is not allowed and leads to killing the page. I want to make an exception for that when I delete files.

When deleting files, the url string always looks like this:

example.com/sfm?delete=uploads/sfm/c4ca4238a0b923820dcc509a6f75849b/folder1

or

example.com/sfm?delete=uploads/sfm/c4ca4238a0b923820dcc509a6f75849b/file.jpg

or

example.com/sfm?delete=uploads/sfm/c4ca4238a0b923820dcc509a6f75849b/folder1/file.jpg

So the minimum of the string contains always:

example.com/sfm?delete=uploads/sfm/c4ca4238a0b923820dcc509a6f75849b

( the hash is a md5 hash of a userid)

So how can I grab that minimum url string?

1. Is the hash always the same size? 2. Does uploads/sfm/ always come? — Praveen Kumar Purushothaman
– Praveen Kumar Purushothaman, Commented May 5, 2016 at 14:32
yes the hash has always the same number of characters and also uploads/sfm is always in the string — Jack Maessen
– Jack Maessen, Commented May 5, 2016 at 14:34

Murad Hasan · Accepted Answer · 2016-05-05 14:49:26Z

1

Use implode, array_slice, explode.

Explode will extract the string to array, array slice cut the array upto 4th item, and implode will grab the array items to a new string.

$str = 'example.com/sfm?delete=uploads/sfm/c4ca4238a0b923820dcc509a6f75849b/folder1 ';

echo $output = implode('/', array_slice(explode("/", $str), 0, 4)); //example.com/sfm?delete=uploads/sfm/c4ca4238a0b923820dcc509a6f75849b

answered May 5, 2016 at 14:49

Murad Hasan

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4 Comments

Praveen Kumar Purushothaman Over a year ago

What does array_slice do here?

Murad Hasan Over a year ago

array_slice takes the selected parts of an array. here takes the index from 0 to 4.

Praveen Kumar Purushothaman Over a year ago

Already you are limiting the explode to 4 right? I mean, I just noticed. You can actually limit it to 4 using explode("/", $str, 4).

Murad Hasan Over a year ago

may be, but i did it this way. i will try that later.

Praveen Kumar Purushothaman · Accepted Answer · 2016-05-05 14:34:59Z

1

I would just use explode(). Even if the hash is not of the same size, if you follow the same structure, I would just do this:

$delete = explode("/", $_GET["delete"]);
print_r($delete);

Outputs to:

Array
(
    [0] => uploads
    [1] => sfm
    [2] => c4ca4238a0b923820dcc509a6f75849b
    [3] => folder1
)

The $delete[2] will give me the hash. I guess this would be the best way, even if the URL changes.

answered May 5, 2016 at 14:34

Praveen Kumar Purushothaman

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