PHP Incrementing and Decrementing Operators


We can use incrementing and decrementing operators to add one or subtract one from a numeric value.


There are two types of incrementing and decrementing operators.


Incrementing and decrementing operators do different things, depending on where you place them.


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


The increment/decrement operators only affect numbers and strings. Arrays, objects and resources are not affected. Decrementing NULL values has no effect too, but incrementing them results in 1.


Operator Name Description
++$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.

The incrementing and decrementing operators can be placed either before or after a variable, and the effect is different depending on where the operator is placed.


Example


		 		<?php
				      $a = 5; 
				      $b = $a++; 
				      print "a is $a\n"; 
				      print "b is $b\n"; 
				      
				      
				      $counter=1;
				      $counter--;
				      echo $counter      
				?>
		 

Example


		 	<?php
		 		  $VisitorsToday = 1;

				  //prints 1
				  print($VisitorsToday++);

				  //VisitorsToday is now 2
				  print("<br>\n");

				  //prints 3
				  print(++$VisitorsToday);
				  print("<br>\n");

				  //prints 4.14
				  $pi = 3.14;
				  $pi++;
				  print($pi);
				  print("<br>\n");

				  //prints PHQ
				  $php = "PHP";
				  $php++;
				  print($php);
				  print("<br>\n");

				  //prints PHP
				  $php = "PHP";
				  $php--;
				  print($php);
				  print("<br>\n");
		 	?>
		 

Example


		 	<?php
		 		$x = 10;  
				echo ++$x;
		 	?>
		 


Example


		 	<?php
		 		$x = 10;  
				echo $x++;
		 	?>
		 

Example


		 	<?php
		 		$x = 10;  
				echo --$x;
		 	?>
		 

Example


		 	<?php
		 		$x = 10;  
				echo $x--;
		 	?>
		 

Example


		 	<?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";
		 	?>
		 

Example


		 	<?php
		 		echo '== Alphabets ==' . PHP_EOL;
				$s = 'W';
				for ($n=0; $n<6; $n++) {
				    echo ++$s . PHP_EOL;
				}
				// Digit characters behave differently
				echo '== Digits ==' . PHP_EOL;
				$d = 'A8';
				for ($n=0; $n<6; $n++) {
				    echo ++$d . PHP_EOL;
				}
				$d = 'A08';
				for ($n=0; $n<6; $n++) {
				    echo ++$d . PHP_EOL;
				}
		 	?>
		 




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