An operator with a higher precedence is executed before an operator with lower precedence.
Precedence of Some PHP Operators (Highest First)
A list of the operators in order of precedence (highest first):
++ -- (increment/decrement) (int) (float) (string) (array) (object) (bool) (casting) ! (not) * / % (arithmetic) + - . (arithmetic) < < = > > = < > (comparison) == != === !== (comparison) && (and) || (or) = += - = *= /= .= %= (assignment) and xor or