What are potential causes for incorrect outputs in PHP code despite correct syntax?

Potential causes for incorrect outputs in PHP code despite correct syntax could include logical errors, incorrect variable usage, or issues with data types. To solve this issue, carefully review the code for any mistakes in logic or variable assignments, ensure that data types are consistent throughout the code, and use debugging tools like var_dump() or print_r() to inspect variables and values at different points in the code.

// Example code snippet to demonstrate debugging and fixing incorrect outputs
$number1 = 10;
$number2 = 20;

// Incorrect addition of two numbers
$result = $number1 . $number2;

// Use var_dump() to inspect the values of variables
var_dump($result);

// Correct addition of two numbers
$correct_result = $number1 + $number2;

echo $correct_result;