PHP Exercises: Exchange the first and last characters in a given string and return the new string

Last update on May 30 2022 11:41:16 (UTC/GMT +8 hours)

PHP Basic Algorithm: Exercise-7 with Solution

Write a PHP program to exchange the first and last characters in a given string and return the new string.

Sample Solution:

PHP Code :

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

echo test("abcd")."\n";
echo test("a")."\n";
echo test("xy")."\n";

Sample Output:

dbca
a
yx

Pictorial Presentation:

PHP Basic Algorithm Exercises: Remove the character in a given position of a given string.

Flowchart:

PHP Code Editor:

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Previous: Write a PHP program to remove the character in a given position of a given string. The given position will be in the range 0..string length -1 inclusive.
Next: Write a PHP program to create a new string which is 4 copies of the 2 front characters of a given string. If the given string length is less than 2 return the original 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