How can multiple variables be checked for existence in PHP?

When checking for the existence of multiple variables in PHP, you can use the isset() function to determine if a variable has been set and is not NULL. You can check each variable individually using isset() or use a shorthand method by using isset() with multiple variables separated by commas.

// Check if multiple variables exist using isset() individually
if(isset($var1) && isset($var2) && isset($var3)) {
    // Variables $var1, $var2, and $var3 exist
}

// Check if multiple variables exist using isset() with shorthand method
if(isset($var1, $var2, $var3)) {
    // Variables $var1, $var2, and $var3 exist
}