In PHP, what is the difference between using strlen(trim($var)) and empty($var) to check for empty strings?

When checking for empty strings in PHP, using `empty($var)` is a more concise and efficient way to determine if a string is empty compared to `strlen(trim($var))`. The `empty()` function not only checks if a variable is empty but also considers values like `0`, `false`, an empty array, or a string with only whitespace characters as empty. On the other hand, `strlen(trim($var))` trims any whitespace from the string and then checks its length, which may not be necessary for just checking emptiness.

// Using empty() function to check for empty strings
if (empty($var)) {
    echo "The string is empty";
} else {
    echo "The string is not empty";
}