PHP Operator Precedence

Operator precedence in PHP determines how expressions involving more than one operator are evaluated. It's similar to the order of operations in mathematics. Operators with higher precedence are evaluated before operators with lower precedence.

Here is a list of PHP operators ordered by their precedence, with the highest-precedence operators listed first:

clone and new
[]
**
++ and -- (postfix)
++ and -- (prefix), ~, (int), (float), (string), (array), (object), (bool), @
instanceof
!
*, /, %
+, -, .
<<, >>
<, <=, >, >=
==, !=, ===, !==
&
^
|
&&
||
??
?: (ternary operator)
= (assignment), +=, -=, *=, /=, .= etc.
and
xor
or

Here's an example of how operator precedence works in PHP:

$a = 2;
$b = 3;
$c = 4;

$result = $a + $b * $c;

In this example, the multiplication (*) is done first, because it has higher precedence than addition (+). So the result is 2 + (3 * 4) = 14, not (2 + 3) * 4 = 20.

If you want to change the order of operations, you can use parentheses, just like in mathematics:

$result = ($a + $b) * $c; // Result is now 20

In this example, the addition is done first because it's inside parentheses. So the result is (2 + 3) * 4 = 20.

It's always a good idea to use parentheses when you're working with complex expressions, even if they're not technically necessary. They make your code easier to read and understand, and they help prevent bugs caused by unexpected order of operations.

Parentheses and changing precedence in PHP expressions:

Parentheses can be used to explicitly change the precedence of operators.

$result = 2 + 3 * 4;      // Multiplication has higher precedence
$result_with_paren = (2 + 3) * 4;  // Addition has higher precedence with parentheses

Comparing and combining different operators in PHP:
- Combining arithmetic, logical, and comparison operators.
```
$value = (5 * 2) / 3 + (10 % 4) == 4 && true;
```
Examples of complex expressions and their evaluation in PHP:
- Evaluate complex expressions based on operator precedence.
```
$result = 2 + 3 * (4 / 2) % 5;  // Result: 4
```
Pitfalls and common mistakes related to operator precedence in PHP:
- Forgetting to use parentheses when needed, leading to unexpected results.
- Assuming operators with similar precedence always evaluate left to right.
```
$result = 2 + 3 * 4;  // Mistakenly assuming addition is evaluated first
```
Mixing logical, arithmetic, and bitwise operators in PHP:
- Combining different types of operators in expressions.
```
$result = (5 > 3) && (10 + 2) | 8;  // Logical AND, arithmetic addition, bitwise OR
```