What's the difference between 'isset()' and '!empty()' in PHP?

Question

I don't understand the difference between isset() and !empty().

Because if a variable has been set, isn't it the same as not being empty?

Solution 1

ISSET checks the variable to see if it has been set. In other words, it checks to see if the variable is any value except NULL or not assigned a value. ISSET returns TRUE if the variable exists and has a value other than NULL. That means variables assigned a "", 0, "0", or FALSE are set, and therefore are TRUE for ISSET.

EMPTY checks to see if a variable is empty. Empty is interpreted as: "" (an empty string), 0 (integer), 0.0 (float)`, "0" (string), NULL, FALSE, array() (an empty array), and "$var;" (a variable declared, but without a value in a class.

For more information, see this article

Solution 2

Source :http://php.net/manual/en/types.comparisons.phpThis page shows the comparison of the empty(),is_null(),isset().

Solution 3

The type comparison tables gives answer of all question about these operators

http://php.net/manual/en/types.comparisons.php

Solution 4

And one more remark. empty() checks if the variable exists as well. I.e. if we perform empty() to the variable that wasn't declared, we don't receive an error, empty() returns 'true'. Therefore we may avoid isset() if next we need to check if the variable empty.

So

isset($var) && !empty($var)

will be equals to

!empty($var)

View more solutions

Comments

[George]

Have you read the manual for both? Here and here

[hek2mgl]

Read this kunststube.net/isset in addition. Thanks @deceze

[Prime]

isset(); checks if the variable is literally set, as in the variable actually points to a value something. empty(); checks if the value the variable points to contains anything.

[hek2mgl]

!isset(NULL) === empty(NULL).

[Gromski]

So how is "empty" defined? Insufficient explanation.

[EresDev]

" " is not empty. "" is empty.

[Unbreakable]

Can you give one example where the isset is true but empty is false. Also an example where isset is false but empty is true?

[Istiaque Ahmed]

@Unbreakable, If '$a=true', then isset() is true but empty() is false. If $a=null, then empty() is true but isset() is false

[Nathan]

I know this is an old question, but is there a difference between if ($variable) {} and if (!empty($variable)) {} ?