how to remove parts of a string after a certian point code example

Example 1: php remove everything after character

$fullpath = 'folderName/file.ext';
$folder = substr($fullpath, 0, strpos($fullpath, '/'));
echo $folder;
// Output => folderName

Example 2: php remove after character

$s = 'Posted On April 6th By Some Dude';
echo strstr($s, 'By', true); // Posted On April 6th