Replace repeating value with zero in PHP string

You can do a array_unique (preserves key), then fill the gaps with 0. Sort by key and you are done :)

+ on arrays will unify the arrays but prioritizes the one on the left.

Code

$input = "0-1-1-3-1-1-3-5-0";
$array = explode('-', $input);
$result = array_unique($array) + array_fill(0, count($array), 0);
ksort($result);

var_dump(implode('-',$result));

Code (v2 - suggested by mickmackusa) - shorter and easier to understand

Fill an array of the size of the input array. And replace by leftover values from array_unique. No ksort needed. 0s will be replaced at the preserved keys of array_unique.

$input = "0-1-1-3-1-1-3-5-0";
$array = explode('-', $input);
$result = array_replace(array_fill(0, count($array), 0), array_unique($array));
var_export($result);

Working example.

Output

string(17) "0-1-0-3-0-0-0-5-0"

Working example.

references

• ksort - sort by key
• array_fill - generate an array filled with 0 of a certain length

This is another way to do it.

$id = "202883-202882-202882-0-234567-2-2-45435";

From the String you explode the string into an array based on the delimiter which in this case is '-'/

$id_array = explode('-', $id);

Then we can loop through the array and for every unique entry we find, we can store it in another array. Thus we are building an array as we search through the array.

$id_array_temp = [];
// Loop through the array
foreach ($id_array as $value) {
    if ( in_array($value, $id_array_temp)) {
        // If the entry exists, replace it with a 0
        $id_array_temp[] = 0;
    } else {
        // If the entry does not exist, save the value so we can inspect it on the next loop.
        $id_array_temp[] = $value;
    }
}

At the end of this operation we will have an array of unique values with any duplicates replaced with a 0.

To recreate the string, we can use implode...

$str = implode('-', $id_array_temp);
echo $str;

Refactoring this, using a ternary to replace the If,else...

$id_array = explode('-', $id);
$id_array_temp = [];
foreach ($id_array as $value) {
    $id_array_temp[] = in_array($value, $id_array_temp) ? 0 : $value;
}
$str = implode('-', $id_array_temp);
echo $str;

Output is

202883-202882-0-0-234567-2-0-45435

This appears to be a classic XY Problem.

The essential actions only need to be:

1. Separate the substrings in the hyphen delimited string.
2. Validate that the characters in each substring are in the correct format AND are unique to the set.
3. Only take meaningful action on qualifying value.

You see, there is no benefit to replacing/sanitizing anything when you only really need to validate the input data. Adding zeros to your input just creates more work later.

In short, you should use a direct approach similar to this flow:

if (!empty($_GET['id'])) {
    $ids = array_unique(explode('-', $_GET['id']));
    foreach ($ids as $id) {
        if (ctype_digit($id) && strlen($id) === 6) {
        // or: if (preg_match('~^\d{6}$~', $id)) {
            takeYourNecessaryAction($id);
        }
    }
}