isset() vs. !empty(): When Should You Use Each Function?

When to Use isset() and !empty()

The isset() function in PHP determines if a variable has been set and is not NULL. It returns TRUE if the variable exists, regardless of its value, including empty strings, 0, and false.

In contrast, the !empty() function checks if a variable is empty. An empty value is defined as an empty string, 0, NULL, false, an empty array, or an empty object. It returns TRUE if the variable is not empty, and FALSE if it is empty.

To decide whether to use isset() or !empty(), consider the following:

When to Use isset()

Use isset() to check if a variable has been set, regardless of its value. This is useful when you want to ensure that a variable exists before accessing its value. For example, you may use isset() to check if a form input has been submitted before accessing its value:

<code class="php">if (isset($_POST['submit'])) {
  // Form has been submitted
}</code>

When to Use !empty()

Use !empty() to check if a variable is not empty. This is useful when you want to ensure that a variable contains a non-empty value. For example, you may use !empty() to check if a user has entered text in a text input:

<code class="php">if (!empty($_POST['username'])) {
  // Username has been entered
}</code>

In your example, you have a $_GET['gender'] variable. To check if it has been set, use isset():

<code class="php">if (isset($_GET['gender'])) {
  // Gender has been set
}</code>

To check if it is not empty, use !empty():

<code class="php">if (!empty($_GET['gender'])) {
  // Gender has a non-empty value
}</code>

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