What are the differences between the 'empty' and 'isset' functions in PHP, and why is it important to understand their distinctions for effective programming?

The main difference between the 'empty' and 'isset' functions in PHP is that 'empty' checks if a variable is empty or not set, while 'isset' checks if a variable is set and is not NULL. It is important to understand their distinctions for effective programming because using the wrong function can lead to unexpected behavior in your code.

// Example of using 'isset' and 'empty' functions
$var = '';

// Using 'isset' to check if variable is set
if(isset($var)){
    echo 'Variable is set';
} else {
    echo 'Variable is not set';
}

// Using 'empty' to check if variable is empty
if(empty($var)){
    echo 'Variable is empty';
} else {
    echo 'Variable is not empty';
}