JAWAHARLAL NEHRU TECHNOLOGICAL UNIVERSITY HYDERABAD B.Tech IV Year PHP PROGRAMMING Previous Question Paper (September - 2020 - R16)

PHP is a server-side scripting language. This means that PHP code is executed on the web server rather than in the user's web browser.

When a client requests a PHP file, the server processes the script, performs necessary operations such as database interactions or calculations, and generates HTML output. This resulting HTML is then sent to the client's browser, which only receives the final rendered output and has no access to the original PHP source code. This architecture enhances security and allows for dynamic content generation based on server-side data.

To swap two integer variables without using a third temporary variable, arithmetic operators such as addition and subtraction can be used. The following PHP script demonstrates this logic:

<?php
$a = 10;
$b = 20;

echo "Before swapping: A = $a, B = $b <br>";

$a = $a + $b;
$b = $a - $b;
$a = $a - $b;

echo "After swapping: A = $a, B = $b";
?>

The logic works by storing the sum of both numbers in the first variable, then subtracting the original value of the second variable from the sum to isolate the first value, and finally subtracting the new value of the second variable from the sum to isolate the second value.