What are some common pitfalls when comparing values in PHP, especially when dealing with NULL values?

When comparing values in PHP, especially when dealing with NULL values, a common pitfall is using the == operator instead of the === operator. The == operator performs type juggling, which can lead to unexpected results when comparing NULL values. To avoid this issue, always use the === operator, which performs a strict comparison without type coercion. 

// Incorrect comparison using ==
$var1 = NULL;
$var2 = 0;

if ($var1 == $var2) {
    echo "Values are equal";
} else {
    echo "Values are not equal";
}

// Correct comparison using ===
$var1 = NULL;
$var2 = 0;

if ($var1 === $var2) {
    echo "Values are equal";
} else {
    echo "Values are not equal";
}

Keywords

PHP comparison operators NULL values type juggling strict comparison

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