What are the potential pitfalls of using assignment operators instead of comparison operators in PHP login scripts?

Using assignment operators instead of comparison operators in PHP login scripts can lead to unintended consequences, such as always assigning a value to a variable instead of checking if it meets a certain condition. This can result in the login script always allowing access, regardless of the validity of the credentials provided. To fix this issue, make sure to use comparison operators (e.g., == or ===) when checking conditions in the login script.

// Incorrect usage of assignment operator
if ($username = 'admin' && $password = 'password') {
    // This condition will always be true due to assignment operators
    echo 'Login successful';
}

// Correct usage of comparison operator
if ($username == 'admin' && $password == 'password') {
    // This condition will only be true if both username and password match
    echo 'Login successful';
}