if（$ variable）和if（isset（$ variable））之间的区别

Question

What is the difference between something like this:

if(isset($variable)) { 

  do_something(); 

}

and this

if($variable) { 

  do_something(); 

}

I want to say that the first case, isset checks to see if the variable exists and is not null. But what if it's set to an empty array?

In the second case, I want to say that if the variable has been instantiated at all, it will pass as true.

Thank you for any future clarification.

Answer 1

if(isset($variable))

checks if the variable exists and is set (different from NULL).

if($variable)

just checks what boolean the variable sends back, in this case its like

if($variable === true)