   #PHP Manual Operators Execution Operators Logical Operators

             PHP Manual
   Prev Chapter 10. Operators Next
   ______________________________________________________________________

Incrementing/Decrementing Operators

   PHP supports C-style pre- and post-increment and decrement operators.

   Table 10-5. Increment/decrement Operators
   Example Name           Effect
   ++$a    Pre-increment  Increments $a by one, then returns $a.
   $a++    Post-increment Returns $a, then increments $a by one.
   --$a    Pre-decrement  Decrements $a by one, then returns $a.
   $a--    Post-decrement Returns $a, then decrements $a by one.

   Here's a simple example script:

   <?php
   echo "<h3>Postincrement</h3>";
   $a = 5;
   echo "Should be 5: " . $a++ . "<br />\n";
   echo "Should be 6: " . $a . "<br />\n";
   echo "<h3>Preincrement</h3>";
   $a = 5;
   echo "Should be 6: " . ++$a . "<br />\n";
   echo "Should be 6: " . $a . "<br />\n";
   echo "<h3>Postdecrement</h3>";
   $a = 5;
   echo "Should be 5: " . $a-- . "<br />\n";
   echo "Should be 4: " . $a . "<br />\n";
   echo "<h3>Predecrement</h3>";
   $a = 5;
   echo "Should be 4: " . --$a . "<br />\n";
   echo "Should be 4: " . $a . "<br />\n";
   ?>

   PHP follows Perl's convention when dealing with arithmetic operations
   on character variables and not C's. For example, in Perl 'Z'+1 turns
   into 'AA', while in C 'Z'+1 turns into '[' ( ord('Z') == 90, ord('[')
   == 91 ). Note that character variables can be incremented but not
   decremented.

   Example 10-1. Arithmetic Operations on Character Variables
   <?php
   $i = 'W';
   for($n=0; $n<6; $n++)
     echo ++$i . "\n";
   /*
     Produces the output similar to the following:
   X
   Y
   Z
   AA
   AB
   AC
   */
   ?>
   ______________________________________________________________________

   Prev                Home              Next
   Execution Operators  Up  Logical Operators
