Operator Precedence
The precedence of an operator specifies how "tightly" it binds two
expressions together. For example, in the expression 1 +
5 * 3, the answer is 16 and not
18 because the multiplication ("*") operator
has a higher precedence than the addition ("+") operator.
Parentheses may be used to force precedence, if necessary. For
instance: (1 + 5) * 3 evaluates to
18.
The following table lists the precedence of operators with the
lowest-precedence operators listed first.
Table 11-1. Operator Precedence
| Associativity | Operators |
|---|
| left | , |
| left | or |
| left | xor |
| left | and |
| right | print |
| left |
= += -= *= /= .= %= &= |= ^= ~= <<= >>=
|
| left | ? : |
| left | || |
| left | && |
| left | | |
| left | ^ |
| left | & |
| non-associative | == != === !== |
| non-associative | < <= > >= |
| left | << >> |
| left | + - . |
| left | * / % |
| right | ! ~ ++ -- (int) (float) (string) (array) (object) @ |
| right | [ |
| non-associative | new |
Note:
Although ! has a higher precedence than
=, PHP will still allow expressions
similar to the following: if (!$a = foo()),
in which case the output from foo() is
put into $a.
