Values and Types

Booleans and Null

Booleans represent true-or-false answers, while null marks a missing value.

Booleans and Null

booleans_null.php 
<?php
$stock = ;
$hasStock = $stock > 0;
$label = null;

if ($hasStock) {
    $label = "ready";
} else {
    $label = "empty";
}

echo "stock=" . $stock . "\n";
echo "hasStock=" . ($hasStock ? "true" : "false") . "\n";
echo "label=" . $label . "\n";

<?php
$stock = ;
$hasStock = $stock > 0;
$label = null;

if ($hasStock) {
    $label = "ready";
} else {
    $label = "empty";
}

echo "stock=" . $stock . "\n";
echo "hasStock=" . ($hasStock ? "true" : "false") . "\n";
echo "label=" . $label . "\n";

<?php
$stock = ;
$hasStock = $stock > 0;
$label = null;

if ($hasStock) {
    $label = "ready";
} else {
    $label = "empty";
}

echo "stock=" . $stock . "\n";
echo "hasStock=" . ($hasStock ? "true" : "false") . "\n";
echo "label=" . $label . "\n";
null `null` means a variable has no useful value yet.