为什么不像对待数学问题一样对待它?

Why not treat it like the math problem it is?

$ i =($ ar [3]< 24)+($ ar [2]< 16)+($ ar [1]< 8)+ $ ar [0] ;

$i = ($ar[3]<<24) + ($ar[2]<<16) + ($ar[1]<<8) + $ar[0];