What common mistake do beginners make when using if() statements in PHP?

One common mistake beginners make when using if() statements in PHP is using a single equal sign (=) for comparison instead of a double equal sign (==) or triple equal sign (===). This mistake can lead to unintended results as a single equal sign is used for assignment, not comparison. To fix this issue, always use double or triple equal signs for comparison in if() statements.

// Incorrect usage of single equal sign for comparison
$number = 5;
if($number = 5) {
    echo "Number is 5";
}

// Correct usage of double equal sign for comparison
$number = 5;
if($number == 5) {
    echo "Number is 5";
}