A.trim()B.rtrim()C.ltrim()D.righttrim()
A.substr()B.count()C.length()D.str_replace()
A.array(’username’=>’lisi’,array(’张三’,’王五’))B.array(1=>"a",2=>"b",3=>"c");C.array(0=>"a",’b’=>1,’a’=>"ab");D.array("a"=>1,"b"=>2,"c"=>3);