PHP另类输出Hello world!

php代码

define(_,'chr(');
define(__,').');
define(___,"print ");
define(____,"'!';");
define(_____,_."0x48".__._."0x65".__._."0x6C".__._."0x6C".__);
define(______,_."0x6F".__._."0x20".__._."0x77".__._."0x6F".__);
define(_______,_."0x72".__._."0x6C".__._."0x64".__);
define(________,_____.______._______);
define(_________,___.________.____);
eval(_________);