Why do I need the isset() function in php?
I am trying to understand the difference between this:
if (isset($_POST['Submit'])) {
//do something
}
and
if ($_POST['Submit']) {
//do something
}
It seems to me that if the $_POST['Submit'] variable is tr开发者_开发技巧ue, then it is set. Why would I need the isset() function in this case?
Because
$a = array("x" => "0");
if ($a["x"])
echo "This branch is not executed";
if (isset($a["x"]))
echo "But this will";
(See also http://hk.php.net/manual/en/function.isset.php and http://hk.php.net/manual/en/language.types.boolean.php#language.types.boolean.casting)
isset will return TRUE if it exists and is not NULL otherwise it is FALSE.
You basically want to check if the $_POST[] variable has been submitted at all, regardless of value. If you do not use isset(), certain submissions like submit=0
will fail.
In your 2nd example, PHP will issue a notice (on E_NOTICE
or stricter) if that key is not set for $_POST
.
Also see this question on Stack Overflow.
The code
if($_POST['Submit'])
{
//some code
}
will not work in WAMP (works on xampp)
on WAMP you will have to use
if (isset($_POST['Submit'])) {
//do something
}
try it. :)
if user do not enter a value so $_post[] return NULL that we say in the description of isset:"
isset will return TRUE if it exists and is not NULL otherwise it is FALSE.,but in here isset return the true "
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