Increment Operator ( ++ )

Incremental Operator (++) is used to increase value of a variable.

<?php
$num=5;
$num++;
echo $num;
?>

Displays the output as 6.

Decrement operator ( -- )

Decremental Operator (--) is used to decrease value of a variable.

<?php
$num=5;
$num--;
echo $num;
?>

Displays the output as 4.

Preincrement operator and Predecrement operator

Example

<?php
$num="5";
echo ++$num;
echo "<BR>";
echo $num;
?>

Displays the output as 6. One more 6 will be displayed in the next line due to BR command.

Similarly, for Pre decrement operator echo --$num; can be used.