What are the potential pitfalls of concatenating numbers as strings in PHP?

Concatenating numbers as strings in PHP can lead to unexpected results when performing arithmetic operations or comparisons. This is because PHP may implicitly convert the strings back to numbers, leading to unintended behavior. To avoid this issue, it is recommended to explicitly cast the strings to numbers before performing any calculations or comparisons.

$num1 = "10";
$num2 = "20";

// Cast the strings to integers before performing any arithmetic operations
$result = (int)$num1 + (int)$num2;

echo $result; // Output: 30