(PHP 4 >= 4.0.6, PHP 5)
mb_substitute_character — Set/Get substitution character
Specifies a substitution character when input character encoding is invalid or character code does not exist in output character encoding. Invalid characters may be substituted NULL (no output), string or integer value (Unicode character code value).
This setting affects mb_convert_encoding(), mb_convert_variables(), mb_output_handler(), and mb_send_mail().
If substchar is set, it returns TRUE for success, otherwise returns FALSE. If substchar is not set, it returns the Unicode value, or "none" or "long".
Example #1 mb_substitute_character() example
<?php
/* Set with Unicode U+3013 (GETA MARK) */
mb_substitute_character(0x3013);
/* Set hex format */
mb_substitute_character("long");
/* Display current setting */
echo mb_substitute_character();
?>