> ## Documentation Index
> Fetch the complete documentation index at: https://docs.syntblaze.com/llms.txt
> Use this file to discover all available pages before exploring further.
# PHP Logical XOR
The `xor` (exclusive OR) operator is a logical operator in PHP that evaluates to `true` if and only if exactly one of its operands evaluates to `true`. If both operands evaluate to `true`, or both evaluate to `false`, the expression returns `false`.
## Syntax
```php theme={"dark"}
$a xor $b
```
## Truth Table
The evaluation logic follows strict exclusive disjunction:
| `$a` | `$b` | `$a xor $b` |
| :------ | :------ | :---------- |
| `true` | `true` | `false` |
| `true` | `false` | `true` |
| `false` | `true` | `true` |
| `false` | `false` | `false` |
## Implicit Boolean Casting
Before evaluation, PHP implicitly casts non-boolean operands to boolean values according to standard PHP type-juggling rules.
```php theme={"dark"}
var_dump(1 xor 0); // bool(true) -> (true xor false)
var_dump("string" xor 1); // bool(false) -> (true xor true)
var_dump("" xor null); // bool(false) -> (false xor false)
```
## Operator Precedence
A critical mechanical detail of the `xor` operator is its position in the operator precedence table. `xor` has a lower precedence than the assignment operator (`=`). This requires explicit grouping via parentheses when assigning the result of an `xor` operation to a variable.
```php theme={"dark"}
// Without parentheses: Assignment takes precedence
$result = true xor false;
// Evaluated as: ($result = true) xor false;
var_dump($result); // bool(true)
$result = true xor true;
// Evaluated as: ($result = true) xor true;
var_dump($result); // bool(true) - Incorrect logical result for the variable
// With parentheses: XOR takes precedence
$result = (true xor true);
var_dump($result); // bool(false) - Correct logical result
```
## Logical `xor` vs. Bitwise `^`
The `xor` operator is strictly a logical operator returning a boolean. It should not be confused with the caret symbol (`^`), which is the bitwise XOR operator. The bitwise operator evaluates the operands at the binary level and returns an integer or string, whereas the logical `xor` evaluates truthiness.
```php theme={"dark"}
// Logical XOR
var_dump(3 xor 6);
// Evaluates as: (true xor true)
// Returns: bool(false)
// Bitwise XOR
var_dump(3 ^ 6);
// Evaluates as: 011 ^ 110 (binary)
// Returns: int(5)
```
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