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<?php mb_substitute_character("long"); var_dump( $conv = mb_convert_encoding( $bin = hex2bin("70000000"), "UTF-8", "UCS-4BE" ), mb_check_encoding($bin, "UCS-4BE"), bin2hex(mb_convert_encoding($conv, "UCS-4BE", "UTF-8")) );
Output for 8.1.0 - 8.1.15, 8.2.0 - 8.2.2
string(10) "U+70000000" bool(true) string(80) "000000550000002b0000003700000030000000300000003000000030000000300000003000000030"
Output for 7.4.0 - 7.4.33, 8.0.1 - 8.0.27
string(3) "?+0" bool(false) string(24) "0000003f0000002b00000030"

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