isset和空中的PHP行为异常

Question

array(4) { ["id"]=>  int(0) ["pass"]=>  string(0) "" ["log_in"]=>  string(3) "no"  } 

The problem in id when using isset it return true because it's 0 . When using empty I think it's doing the same. What is the best function to know whether it's set or not?

Answer 1

empty returns false for these:

• "" (an empty string)
• 0 (0 as an integer)
• "0" (0 as a string)
• NULL
• FALSE
• array() (an empty array)
• var $var (a variable declared, but without a value in a class)

You need to use isset instead to check if it is there.

See this article on empty vs isset for more info.

Answer 2

if($array['id'] === 0) {
  true
} ?

Answer 3

在PHP站点上查看此图表 。

Answer 4

a simple if condition will do for you

if(id)
{
}

try it if it works.

Answer 5

if id is a database id is positive integer

so if($id>0) is one simple solution

OR

preg_match('#^[0-9]*$#', $id)

another