`isset()` vs. `empty()`: When Should You Use Each for PHP Variable Evaluation?

isset() versus empty() for Variable Evaluation

In coding, it is often necessary to assess whether a variable is set or empty. While similar in functionality, the choices between isset() and empty() vary depending on the desired result.

empty()

empty() checks if a variable is set and simultaneously examines its value. It considers variables with the following values as empty:

• "" (empty string)
• 0 (integer)
• 0.0 (float)
• "0" (string)
• NULL
• FALSE
• array() (empty array)
• Undeclared variables

isset()

isset(), on the other hand, solely determines if a variable has been set and is not NULL. It does not consider the variable's value.

Which to Use

The choice between isset() and empty() depends on the desired behavior:

• To check if a variable is both set and not empty (with the exception of NULL), use empty().
• To check if a variable is set, regardless of its value, use isset().

Example

Here's an improved version of the code example provided:

<?php
    $var = '23';
    
    if (!empty($var)) {
        echo 'not empty';
    } else {
        echo 'is not set or empty';
    }
?>

This revised code uses empty() directly without the need for isset() since empty() checks for both the existence and non-empty value of the variable.

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