Str_replace for multiple items
Like this:
str_replace(array(':', '\\', '/', '*'), ' ', $string);
Or, in modern PHP (anything from 5.4 onwards), the slighty less wordy:
str_replace([':', '\\', '/', '*'], ' ', $string);
str_replace() can take an array, so you could do:
$new_str = str_replace(str_split('\\/:*?"<>|'), ' ', $string);
Alternatively you could use preg_replace():
$new_str = preg_replace('~[\\\\/:*?"<>|]~', ' ', $string);