echo - Strange print behaviour in PHP?

Why does the following code output 128?

    print 4 << 5; 
?>

Answer

Because it's a bitwise operator. I think it means 4 multiplied to 2^5 because that operator means

Shift the bits of $a $b steps to the left (each step means "multiply
by two")

so it's five steps. It's 4 * 2 * 2 * 2 * 2 * 2 (But I'm guessing here; everything happens at bit level).