PHP Operators

Operators are used to perform operations on variables and values. PHP divides the operators into the following groups:

1. Arithmetic operators

Arithmetic operators are used to perform common mathematical operations.

+ (Addition)
- (Subtraction)
* (Multiplication)
/ (Division)
% (Modulus)
** (Exponentiation)

2. Assignment operators

Assignment operators are used to write a value to a variable.

= (Assign)
+= (Add and assign)
-= (Subtract and assign)
*= (Multiply and assign)
/= (Divide and assign)
.= (Concatenate and assign)

3. Comparison operators

Comparison operators are used in logical statements to determine equality or difference between variables or values.

== (Equal)
=== (Identical)
!= (Not equal)
!== (Not identical)
< (Less than)
> (Greater than)
<= (Less than or equal to)
>= (Greater than or equal to)
<=> (Spaceship)

4. Increment/Decrement operators

Increment/decrement operators are used to increment/decrement a variable's value.

++$x (Pre-increment)
$x++ (Post-increment)
--$x (Pre-decrement)
$x-- (Post-decrement)

5. Logical operators

Logical operators are used to combine conditional statements.

and (And)
or (Or)
xor (Xor)
&& (And)
|| (Or)
! (Not)

6. String operators

String operators are used to manipulate strings.

. (Concatenation)
.= (Concatenation assignment)

7. Array operators

Array operators are used to compare arrays.

+ (Union)
== (Equality)
=== (Identity)
!= (Inequality)
<> (Inequality)
!== (Non-identity)

8. Conditional assignment operators

Conditional assignment operators are used to set a value depending on conditions.

?: (Ternary)
?? (Null coalescing)

Example:

$x = 10;
$y = 20;

// Arithmetic operator
echo $x + $y; // 30

// Assignment operator
$x += $y; // $x = $x + $y; $x = 30

// Comparison operator
if ($x == $y) {
    echo "Equal";
} else {
    echo "Not equal";
}

// Increment operator
$x++; // 31

// Logical operator
if ($x > 0 and $y > 0) {
    echo "Both are positive numbers";
}

// String operator
$txt1 = "Hello";
$txt2 = "World";
echo $txt1 . $txt2; // HelloWorld

// Array operator
$array1 = array("a" => "red", "b" => "green");
$array2 = array("c" => "blue", "d" => "yellow");
print_r($array1 + $array2); // Union of $array1 and $array2

// Conditional assignment operator
$user = isset($user) ? $user : 'guest'; // If $user is set then assign its own value, otherwise assign 'guest'
$user = $user ?? 'guest'; // PHP 7+ version of the above code
``

Arithmetic operators in PHP:

Common arithmetic operators include +, -, *, /, and %.

$a = 5;
$b = 2;

$sum = $a + $b;   // Addition
$diff = $a - $b;  // Subtraction
$prod = $a * $b;  // Multiplication
$quot = $a / $b;  // Division
$mod = $a % $b;   // Modulus (remainder)

Comparison operators in PHP:

Comparison operators include ==, ===, !=, !==, <, >, <=, and >=.

$x = 5;
$y = 10;

$isEqual = ($x == $y);      // Equal
$isIdentical = ($x === $y); // Identical
$isNotEqual = ($x != $y);   // Not Equal
$isNotIdentical = ($x !== $y); // Not Identical

Logical operators in PHP:

Logical operators include && (and), || (or), ! (not).

$a = true;
$b = false;

$resultAnd = $a && $b;  // Logical AND
$resultOr = $a || $b;   // Logical OR
$resultNot = !$a;        // Logical NOT

Assignment operators in PHP:

Assignment operators include =, +=, -=, *=, /=, and %=.

$x = 5;
$y = 3;

$x += $y;  // Equivalent to $x = $x + $y;
$x *= 2;   // Equivalent to $x = $x * 2;

Bitwise operators in PHP:

Bitwise operators include &, |, ^, ~, <<, and >>.

$a = 5; // binary: 0101
$b = 3; // binary: 0011

$bitwiseAnd = $a & $b;  // binary: 0001
$bitwiseOr = $a | $b;   // binary: 0111

Increment and decrement operators in PHP:
- Increment (++) and decrement (--) operators.
```
$num = 5;

$num++; // Increment by 1
$num--; // Decrement by 1
```
Ternary (conditional) operator in PHP:
- The ternary operator (? :) provides a shorthand for if-else statements.
```
$isTrue = true;

$result = $isTrue ? "It's true!" : "It's false!";
```

String concatenation operator in PHP:

The . operator is used for string concatenation.

$str1 = "Hello";
$str2 = "World";

$concatenated = $str1 . " " . $str2; // Output: Hello World