PHP Exercises: Create a new string from a given string after swapping last two characters

Last update on May 30 2022 11:41:28 (UTC/GMT +8 hours)

PHP Basic Algorithm: Exercise-78 with Solution

Write a PHP program to create a new string from a given string after swapping last two characters.

Sample Solution:

PHP Code :

<?php
function test($s1)
{ 
        if (strlen($s1) > 1)
            {
                return substr($s1, 0, strlen($s1) - 2) . substr($s1, strlen($s1)-1, 1) . substr($s1, strlen($s1)-2, 1);
            }
            else
            {
                return $s1;
            }
    }

echo test("Hello")."\n";
echo test("Python")."\n";
echo test("PHP")."\n";
echo test("JS")."\n";
echo test("C")."\n";

Sample Output:

Helol
Pythno
PPH
SJ
C

Flowchart:

PHP Code Editor:

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Previous: Write a PHP program to concat two given strings (lowercase). If there are any double character in new string then omit one character.
Next: Write a PHP program to check if a given string begins with 'abc' or 'xyz'. If the string begins with 'abc' or 'xyz' return 'abc' or 'xyz' otherwise return the empty string.

What is the difficulty level of this exercise?

Test your Programming skills with w3resource's quiz.

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