Question

I love the SUBSTRING_INDEX function in MySQL, especially because you can use negative indexes to start searching from the right side of the string.

Is there an equivalent of this function in PHP? (or an easy way to do it with a bit of code)

Answer 1

There’s no single library function that gets you this same functionality, but you can get a one-liner:

$str = "www.mysql.com";
echo implode('.', array_slice(explode('.', $str), 0, 2)); // prints "www.mysql"
echo implode('.', array_slice(explode('.', $str), -2));   // prints "mysql.com"

Easily turn this into a function:

function substring_index($subject, $delim, $count){
    if($count < 0){
        return implode($delim, array_slice(explode($delim, $subject), $count));
    }else{
        return implode($delim, array_slice(explode($delim, $subject), 0, $count));
    }
}