Returns a string with backslashes before characters that are
charlist parameter. If
charlist contains characters
\n, \r etc., they are
converted in C-like style, while other non-alphanumeric characters
with ASCII codes lower than 32 and higher than 126 converted to
Be careful if you choose to escape characters 0, a, b, f, n, r, t and v. They will be converted to \0, \a, \b, \f, \n, \r, \t and \v. In PHP \0 (NULL), \r (carriage return), \n (newline) and \t (tab) are predefined escape sequences, while in C all of these are predefined escape sequences.
charlist like "\0..\37", which would
escape all characters with ASCII code between 0 and 31.
When you define a sequence of characters in the charlist argument make sure that you know what characters come between the characters that you set as the start and end of the range.