What is the difference between empty and isset usage in php?

What is the difference between empty and isset usage in php? The following article will introduce to you the difference between the usage of empty function and isset function in PHP. It has certain reference value. Friends in need can refer to it. I hope it will be helpful to everyone.

isset

isset returns false only when the variable is null and returns true at any other time

（ In PHP, variables are considered to be null. 1. Variables that have not been assigned or initialized. 2. Variables assigned to null)

$null = null;
$num = 0;
$str = '';
$bool = false;
var_dump(isset($null)); // false
var_dump(isset($num));  // true
var_dump(isset($str));  // true
var_dump(isset($bool)); // true

empty

empty determines whether the variable is empty There are 5 situations where it will return true

1, empty string ''

2, number zero 0

3, bool value false

4. null

5. String zero '0'

$null = null;
$num = 0;
$str = '';$bool = false;var_dump(empty($null)); // true
var_dump(empty($num)); // true
var_dump(empty($snum)); // true
var_dump(empty($str)); // true
var_dump(empty($bool)); // true

Summary:

isset only returns no value when the value is null. false

empty will determine the empty value in 5 situations

Note:The parameters of these two functions can only be variables and not constants

empty(0)
empty('abc')
isset(null)

This way of writing will result in an error

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