1. Operators
Operators are symbols such as + (addition), - (subtraction), and * (multiplication). Operators do something with values. $foo = 25; $foo – 15; // $foo and 15 are the operands, - is the operator

2. Arithmetic Operators + Addition $a + $b - Subtraction $a - $b
* Multiplication $a * $b
/ Division $a / $b
% Modulus (modulus divides the first value by the second, and returns the remainder e.g.
$foo = 9;
echo ($foo % 4);
// 1 )

3. Assignment Operators
Assignment operators set the value of variables = Assignment $a = $b copies $b's value into $a =& Reference $a =& $b set $a to reference $b

4. Concatenation Operator
Concatenation means to put things together. The concatenation operator puts strings together. . Concatenation appends 2nd value to 1st $first = "Barack"; $second = "Obama" Echo ($first . " " . $second); // Barack Obama

5. Comparison Operators
== Equals true if $a = $b === Identical true if $a = $b and of same type $x = 50; // integer $y = "50"; // string if ($x == $y) { echo "$x is the same as $y"; } // 50 is the same as 50

6. $x = 50; // integer
$y = "50"; // string
if ($x === $y) {
echo "$x is the same as $y";
} else {
echo "$x is not the same as $y"; }
// 50 is not the same as 50

7. Comparison Operators
!= Not Equal true if $a is not equal to $b !== Not Identical true if $a is not identical to $b < Less Than true if $a is less than $b > Greater Than true if $a is greater than $b <= Less Than or Equal to >= Greater Than or Equal to

8. Increment/Decrement Operators
++$a pre-increment increments $a by 1, then returns $a $a++ post-increment returns $a, then increments $a by 1 --$a pre-decrement decrements $a by 1, $a-- post-decrement returns $a, then decrements by 1

9. $a = 10;
echo $a++ . "<br />";
echo $a;
// 10 11
echo ++$a;
// 11

10. Logical Operators
AND true if both $a AND $b are true $a = 10; $b = 5; if ($a > 5 AND $b >= 5) { echo "This is pretty cool"; } // This is pretty cool && is the same as AND

11. Logical Operators
OR true if either $a AND $b are true $a = 10; $b = 5; if ($a > 5 OR $b > 5) { echo "This is pretty cool"; } // This is pretty cool || is the same as OR