Comparison of PHP floating-point numbers

Floating point of comparison generally more headaches, before learning C language has no this problem, because the C language has a type of automatic expansion, if two numbers are not the same type will convert another type, so the comparison is a good problem, but PHP is a weak type language, so the comparison of floating-point numbers is a bit problematic, but the official has provided a , specifying the comparison function of the precision comparison floating-point number, such as: http://php.net/manual/en/book.bc.php