Isset()/Empty(), Arrays and Ternary Operator [duplicate]

Question

We've all encountered it before, needing to print a variable in an input field but not knowing for sure whether the var is set, like this. Basically this is to avoid an e_warning.

<input value='<?php if(isset($var)){print($var);}; ?>'>

How can I write this shorter? I'm okay introducing a new function like this:

<input value='<?php printvar('myvar'); ?>'>

But I don't succeed in writing the printvar() function.

Answer 1

For PHP >= 7.0:

As of PHP 7 you can use the null-coalesce operator:

$user = $_GET['user'] ?? 'guest';

Or in your usage:

<?= $myVar ?? '' ?>

For PHP >= 5.x:

My recommendation would be to create a issetor function:

function issetor(&$var, $default = null) {
    return isset($var) ? $var : $default;
}

This takes a variable as argument and returns it, if it exists, or a default value, if it doesn't. Now you can do:

echo issetor($myVar);

But also use it in other cases:

$user = issetor($_GET['user'], 'guest');

Answer 2

Another option:

<input value="<?php echo isset($var) ? $var : '' ?>">

Answer 3

<input value='<?php @print($var); ?>'>

Answer 4

The shortest answer I can come up with is <?php isset($var) AND print($var); ?>

Further details are here on php manual.

A simple alternative to an if statement, which is almost like a ternary operator, is the use of AND. Consider the following:

'; // This is an alternative isset( $value ) AND print( $value ); ?>

This does not work with echo() for some reason. I find this extremely useful!