PHP操作员需要帮助

Question

I'm from C++ background and newbie in php, somebody please help me with the difference between the two:

$totalupdatedrows = (count($rows) == 1 and !isset($rows[0]->updated_by))  ? 0 : count($rows);


$totalupdatedrows = count($rows) == 1 and !isset($rows[0]->updated_by)  ? 0 : count($rows);

assume count($rows) = 1 and $rows[0]->updated_by=null. Please see that first one has only one extra wrapper parentheses.

I'm getting correct result from the first statement. I expect to get result of 0 which is the result of the first one and not the second one. I can't figure out the difference.

Answer 1

and has lower precedence than the ternary operators ( ? and : ). Therefore, you need to wrap it in parenthesis ( ( and ) ) so it is evaluated first.

Note that if you had used && , you would not need to use the extra parenthesis.

Answer 2

Checkout the PHP documentation - Operator Precedence and is nearly last.

If you change your and to && it will sit at a higher order than ?: