What are the potential pitfalls of not using proper variable declarations in PHP?

Not using proper variable declarations in PHP can lead to confusion, errors, and security vulnerabilities in your code. It is important to declare variables before using them to ensure clarity and avoid unexpected behavior. By using proper variable declarations, you can improve the readability and maintainability of your code while reducing the risk of bugs.

// Incorrect way of using variables without proper declaration
$num = 10;
echo $num + $number; // Notice the undefined variable $number

// Correct way of declaring variables before using them
$num = 10;
$number = 5;
echo $num + $number; // Outputs 15