If variable is not set?

How do I say in php if a variable is not set then go to a different page and if it is then continue loading current page?

(I can do if isset fine but for what i'm doing i need it the other way around)

I know I should probably know this since it seems like it would be easy I'm just having a bit of trouble with it and figured someone here could tell me quickly and save me a long drawn out process of figuring what i'm doing wrong. Thank you

 

if(!isset($variable)){
//do something
}

PHP:

the ! means not

 

Try this one:

<?php
if($anyvariable){
echo "Variable is present";
}else{
echo "Variable is NOT present";
}

PHP:

 

That's not right in all cases! Here's an example - if your url is http://test.test/?test
then

if($_GET['test'])

PHP:

will return false, cause the var has no value, but

isset($_GET['test'])

PHP:

will return true, cause the var is set, though it's null.

Just wanted to explain a bit further, cause that's important to know

 

Use:
if (!isset($varname)) {
}

! gives the opposite effect, so the following means 'not equal to':

($var1 != $var2) {

 

I prefer doing stuff on positive side.

if(empty($variable)){
//do something
}

PHP:

Returns FALSE if var has a non-empty and non-zero value.

The following things are considered to be empty:

* "" (an empty string)
* 0 (0 as an integer)
* "0" (0 as a string)
* NULL
* FALSE
* array() (an empty array)
* var $var; (a variable declared, but without a value in a class)