$n = 00000000000000000000000000001011;
$res = 0;
while ($n){
$res += $n&1;
$n>>=1; //向右位移并赋值
}
return $res;
$n = 00000000000000000000000000001011;
$res = 0;
while ($n){
$res += $n&1;
$n>>=1; //向右位移并赋值
}
return $res;