3v4l.org

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<?php var_dump( $conv = mb_convert_encoding( $bin = hex2bin("0001f1e8"), "UTF-8-Mobile#KDDI-A", "UCS-4BE" ), mb_check_encoding($bin, "UTF-8-Mobile#KDDI-A"), bin2hex(mb_convert_encoding($conv, "UTF-8-Mobile#KDDI-A", "UTF-8")) );
Output for 8.1.0 - 8.1.15, 8.2.0 - 8.2.2
string(1) "?" bool(false) string(2) "3f"
Output for 7.4.0 - 7.4.33, 8.0.1 - 8.0.26
string(0) "" bool(false) string(0) ""

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31.71 ms | 407 KiB | 5 Q