isset vs. empty

[leegold2]

isset vs. empty

I'm trying to find a simple explanation and simple examples on what the difference is between these two functions. Appreciate any easy to understand help.

Thanks

 

[sleipnir214]

isset() will tell you whether the variable has been instantiated. empty() will tell you if an existing variable has a value.

For example, if

$a = "foo";
$b = "";

then

isset ($a) will return TRUE
isset ($b) will return TRUE
isset ($c) will return FALSE

empty ($a) will return FALSE
empty ($b) will return TRUE
empty ($c) will, I think, return a warning.

Read the PHP online manual entry for empty() (

http://www.php.net/manual/en/function.empty.php)

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[jpadie]

empty($c) will return true.

an uninstantiated variable is empty for the purposes of the function.

i use isset as a more granular form of empty when i really want to know whether a variable exists (ie form submission).