Php: ++, --: increment and decrement operators

++ Increment operator; increments a value by 1

-- Decrement operator; decrements a value by 1

 

Pre increment

Syntax:

++$variable_name

 

Example

++$a

     

Pre increment operator increments the variable value by 1 immediately.

 

pre_increment_demo.php

#!/usr/bin/php

<?php
$a = 10;

echo "Value of a is " . $a . "\n";
echo "Value of ++a is " . ++$a . "\n";
echo "Value of a is " . $a . "\n";
?>

 

Output

$./pre_increment_demo.php 

Value of a is 10
Value of ++a is 11
Value of a is 11

 

Post increment

In case of post increment operator variable is evaluated first, and increment will be done later.

 

Syntax:

$variable++

 

Syntax

$a++

 

post_increment_demo.php

#!/usr/bin/php

<?php
$a = 10;

echo "Value of a is " . $a . "\n";
echo "Incrementing a twice in the same line " . $a++ . "\t" . $a++ . "\n";
echo "Value of a is " . $a . "\n";
?>

 

Output

$./post_increment_demo.php 

Value of a is 10
Incrementing a twice in the same line 10    11
Value of a is 12

 

Pre decrement

Syntax:

--$variable_name

 

Example

--$a

     

Pre increment operator decrements the variable value by 1 immediately.

 

pre_decrement_demo.php

#!/usr/bin/php

<?php
$a = 10;

echo "Value of a is " . $a . "\n";
echo "Value of --a is " . --$a . "\n";
echo "Value of a is " . $a . "\n";
?>

 

Output

$./pre_decrement_demo.php 

Value of a is 10
Value of --a is 9
Value of a is 9

 

Post decrement

In case of post decrement operator variable is evaluated first, and decrement will be done later.

 

Syntax:

$variable_name--

 

Example

$a--

 

post_decrement_demo.php

#!/usr/bin/php

<?php
$a = 10;

echo "Value of a is " . $a . "\n";
echo "Incrementing a twice in the same line " . $a-- . "\t" . $a-- . "\n";
echo "Value of a is " . $a . "\n";
?>

 

Output

$./post_decrement_demo.php 

Value of a is 10
Incrementing a twice in the same line 10    9
Value of a is 8

 

 

 

 

 

 

 

 

 

 

 

 

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