What is the significance of using a strongly typed comparison operator like "===" in PHP when dealing with undefined variables?

When dealing with undefined variables in PHP, using a strongly typed comparison operator like "===" is significant because it not only compares the values of the variables, but also checks if they are of the same data type. This helps avoid unexpected behavior that can occur when using loosely typed comparison operators like "==", which may treat variables of different data types as equal.

$var1 = 5;
$var2 = "5";

// Using a strongly typed comparison operator
if ($var1 === $var2) {
    echo "The variables are equal in value and data type.";
} else {
    echo "The variables are not equal in value or data type.";
}