PHP Exercises : Swap two variables

Last update on May 30 2022 11:48:16 (UTC/GMT +8 hours)

PHP : Exercise-31 with Solution

Write a PHP program to swap two variables.

PHP: Swapping two variables

Swapping two variables refers to mutually exchanging the values of the variables. Generally, this is done with the data in memory.

The simplest method to swap two variables is to use a third temporary variable :

define swap(a, b)
    temp := a
    a := b
    b := temp

PHP: swap two variables

Sample Solution: -

Code : Swap two numbers using a third variable

PHP Code:

<?php
$a = 15;
$b = 27;
 
// Swap Logic

echo "\nThe number before swapping is:\n";
echo "Number a =".$a." and b=".$b;

$temp = $a;
$a = $b;
$b = $temp;
 
echo "\nThe number after swapping is: \n";
echo "Number a =".$a." and b=".$b."\n";
?>

Code: Swap two variables value without using third variable

<?php
$a = 15;
$b = 276;
echo "\nBefore swapping:  ". $a . ',' . $b;
list($a, $b) = array($b, $a);
echo "\nAfter swapping:  ". $a . ',' . $b."\n";
?>

Sample Output:

The number before swapping is:                              
Number a =15 and b=27                                       
The number after swapping is:                               
Number a =27 and b=15

Flowchart:

PHP Code Editor:

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Previous: Write a PHP script to get the time of the last modification of the current page.
Next: Write a PHP program to check if a number is an Armstrong number or not. Return true if the number is Armstrong otherwise return false.

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PHP: Tips of the Day

How to Sort Multi-dimensional Array by Value?

Try a usort, If you are still on PHP 5.2 or earlier, you'll have to define a sorting function first:

Example:

function sortByOrder($a, $b) {
    return $a['order'] - $b['order'];
}

usort($myArray, 'sortByOrder');

Starting in PHP 5.3, you can use an anonymous function:

usort($myArray, function($a, $b) {
    return $a['order'] - $b['order'];
});

And finally with PHP 7 you can use the spaceship operator:

usort($myArray, function($a, $b) {
    return $a['order'] <=> $b['order'];
});

To extend this to multi-dimensional sorting, reference the second/third sorting elements if the first is zero - best explained below. You can also use this for sorting on sub-elements.

usort($myArray, function($a, $b) {
    $retval = $a['order'] <=> $b['order'];
    if ($retval == 0) {
        $retval = $a['suborder'] <=> $b['suborder'];
        if ($retval == 0) {
            $retval = $a['details']['subsuborder'] <=> $b['details']['subsuborder'];
        }
    }
    return $retval;
});

If you need to retain key associations, use uasort() - see comparison of array sorting functions in the manual

Ref : https://bit.ly/3i77vCC