PHP子串函数导致不同的数据

Question

I am getting unexpected results on my substr() function on PHP. Characters 1 to 6 is ok, but 7 and 8 is not.

$naiyou = '10000010';

$char8 = substr($naiyou  -1, 1);
$char7 = substr($naiyou  -2, 1);    
$char6 = substr($naiyou, -3, 1);    
$char5 = substr($naiyou, -4, 1);    
$char4 = substr($naiyou, -5, 1);    
$char3 = substr($naiyou, -6, 1);
$char2 = substr($naiyou, -7, 1);
$char1 = substr($naiyou, -8, 1);

Character 8 is resulting : 00000009 and Character 7 is resulting : 00000008.

Answer 1

You have missed comma(,) in $char8 and $char7. So it is subtracting and substr() function is getting two parameters instead of three which you intended. The right statement will be:

$char8 = substr($naiyou, -1, 1);
$char7 = substr($naiyou, -2, 1);