Check if string starts with in array values

Question

I have an array of excluded category IDs. I'm trying to fetch data from the DB and filter products based on this array.

1000 is an example of Category Level 1 ID
1000001 is an example of Category Level 2 ID
1000001021 is an example of Category Level 3 ID

So if level 1 is excluded, products of level 2 and 3 are automatically excluded. Currently I'm doing this:

$excludedCategories = ['1000', '100011'];

while ($row = $result->fetch_assoc()) {
    $category = "1". $row['category'] . $row['sub_category'] . $row['category_id'];
    foreach ($excludeCategories as $exCategory) {
        if( substr($category, 0, strlen($exCategory)) === $exCategory ) {
            echo 'Category'. $category . " matches " . $exCategory . "<br>";
            continue;
        }
    }
}

.. but is there a better way of doing it without running the second loop?

preg_match can be used to solve it pretty easy if the array values can be converted to regex pattern if not — codefreaK
– codefreaK, Commented May 13, 2016 at 23:24
@manix Probably not because i need to check IDs that "start with" — eozzy
– eozzy, Commented May 13, 2016 at 23:28
@3zzy Why do you need to loop the excludedCategories if the first start with 1000? I guess the second is automatically excluded, Am I getting this wrong? — Pedro Lobito
– Pedro Lobito, Commented May 13, 2016 at 23:43

Pedro Lobito · Accepted Answer · 2018-04-12 19:47:48Z

8

If you implode $excludedCategories to make a pattern for preg_match, you don't need the loop.

$excludedCategories = ['1000', '100011'];
while ($row = $result->fetch_assoc()) {
    $category = "1". $row['category'] . $row['sub_category'] . $row['category_id'];
        if( preg_match("/^".implode("|",$excludedCategories)."/", $category)) {
            echo "Category: $category Excluded <br>";
     }
}

edited Apr 12, 2018 at 19:47

answered May 13, 2016 at 23:50

Pedro Lobito

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1 Comment

Jan Potužník Over a year ago

In this case it is not a concern, but consider using preg_quote on all items of the array.

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