Arithmetic operation within string concatenation without parenthesis causes strange result

Question

Consider the following line of code:

The output of that is 3, which is the expec

Answer 1

Your string '10 - 7 = ' is being concatenated with $x. Then that is being interpreted as an int which results in 10 and then 7 is subtracted, resulting in 3.

For more explanation, try this:

echo (int) ('10 - 7 = ' . 10); // Prints "10"

More information on string to number conversion can be found at http://www.php.net/manual/en/language.types.string.php#language.types.string.conversion

If the string starts with valid numeric data, this will be the value used