PHP: Remove invalid characters from file names

Characters such as "?", "\", "/", "*" or "|" are not allowed in file names on Windows and other operating systems. With this line of code, you can simply delete those characters from a string with the help of PHP:

$f = 'fi?le.txt';

$f = str_replace(array('\\','/',':','*','?','"','<','>','|'),' ',$f);

echo $f; // 'fi le.txt'

The respective characters are simply replaced by a space.

Alternatively, you can also just use another character instead of the space or write '' to the replace function in order to delete the characters completely.