Avoiding Undefined Variable Errors

[Nick20]

Hey people!

 

I've just come across something when using Larry's config script in PHP Advanced.

 

Now I have the error handler running, it flags up all these undefined variable errors wherever I have this type of thing:

 

$content = $_GET['var']

 

is says that $_GET['var'] isn't defined.

 

I can get round it like this:

 

if(isset($_GET['z_'])){
    $content = $_GET['z_'];
} else {
    $content = FALSE;
}

 

But seems like a really long way around it do to every time I want to rename a GET variable.

 

I have tried sticking it all in a function, but of course, when I pass the GET function into the function, I get the same error.

 

I also seem to need an ELSE, otherwise, I get undefined errors on $content.

 

Is there a better way round this??

 

CHeers,

 

Nick

[Antonio Conte]

You can use a shorter syntax called the ternary operator. It has three parts. The expression, the true value and the false value. The expression is the if-statement, the value/variable after the question mark is used if the expression is true, and the value/variable after ':' is used when the expression is false.

 

// Basic
$var = isset($_GET['var']) ? $_GET['var'] : false;

// Validation is also fine
$var = isset($_GET['var']) ? mysqli_real_escape_string($_GET['var']) : false;

// You can use several expressions too
$var = ( isset($_GET['var']) && is_numeric($_GET['var']) ) ? 'This is a numeric value' : 'Not a numeric value';

 

You can even develop a function for this. Let's take an example with Integers.

 

$var = get_intval($_GET['var'];

// Returns value if it's not null, else false
function get_intval( $var )
{
   return ( $var != null && is_numeric($var) ) ? (int) $var : false;
}

[Nick20]

Thanks Antonio - great tip! Job done