Why use multibyte string functions in PHP?

Question

At the moment, I don\'t understand why it is really important to use mbstring functions in PHP when dealing with UTF-8? My locale under linux is already set

Answer 1

Raul González is a perfect example of why:

It is about shortening too long user names for MySQL database, say we have 10 character limit and Raul González.

The unit test below is an example how you can get an error like this

General error: 1366 Incorrect string value: '\xC3' for column 'name' at row 1 (SQL: update users set name = Raul Gonz▒, updated_at = 2019-03-04 04:28:46 where id = 793)

and how you can avoid it

public function test_substr(): void
{
    $name = 'Raul González';
    $user = factory(User::class)->create(['name' => $name]);
    try {
        $name1      = substr($name, 0, 10);
        $user->name = $name1;
        $user->save();
    } catch (Exception $ex) {

    }
    $this->assertTrue(isset($ex));

    $name2      = mb_substr($name, 0, 10);
    $user->name = $name2;
    $user->save();

    $this->assertTrue(true);
}

PHP Laravel and PhpUnit was used for illustration.