PHP arithmetic Operators are used to perform mathematical calculations.
Increment and Decrement operators act on numeric values.
<?php $var = 1; // Assign the integer 1 to $var echo $var++; // Print 1, $var is now equal to 2 echo ++$var; // Print 3, $var is now equal to 3 echo --$var; // Print 2, $var is now equal to 2 echo $var--; // Print 2, $var is now equal to 1 ?>
By default, assignment operators work by value—that is, they copy the value of an expression on to another. If the right-hand operand happens to be a variable, only its value is copied, so that any subsequent change to the left-hand operator is not reflected in the right-hand one.
<?php $a = 5; $b = $a; $b = 10; echo $a; // Print 5 ?>
Naturally, you expect this to be the case, but there are circumstances in which you may want an assignment to take place by reference so that the left-hand operand becomes "connected" with the right-hand one:
<?php $a = 5; $b = &$a; // Reference $b = 10; echo $a; // Print 10 ?>