How to Effectively Determine Variable Emptiness in PHP: Techniques and Best Practices

Handling Empty Variables: Efficient and Concise Techniques

In many programming scenarios, we encounter situations where we need to check whether a variable is empty. However, there are multiple ways to determine emptiness, each with its own nuances and efficiency considerations.

is_null, empty, or === NULL?

• is_null: Checks if a variable is literally NULL, which is a specific PHP value returned when a variable is explicitly set to NULL.
• empty: Evaluates to TRUE if the variable is NULL, an empty string, an empty array, or 0.
• === NULL: Compares the variable to NULL using the strict equality operator, which evaluates to FALSE if the variable is equal to NULL, but different in type (e.g., an empty string).

Concise Multi-Variable Check

To check multiple variables for emptiness in a single line, consider using an array:

<code class="php">$vars = [$user_id, $user_name, $user_logged];

if (in_array(NULL, $vars)) {
    // At least one variable is empty
}</code>

Determining an Empty String

If you specifically want to check if a variable contains an empty string, compare it with an empty string:

<code class="php">if ($user_id === '') {
    // $user_id is an empty string
}</code>

Not Empty Checks

To check if a variable is not empty (i.e., contains a non-empty value), use:

<code class="php">if (!empty($user_id)) {
    // $user_id contains a non-empty value
}</code>

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