PHP Exercises: Create a new string taking 3 characters from the middle of a given string at least 3

Last update on May 30 2022 11:41:27 (UTC/GMT +8 hours)

PHP Basic Algorithm: Exercise-74 with Solution

Write a PHP program to create a new string taking 3 characters from the middle of a given string at least 3.

Sample Solution:

PHP Code :

<?php
function test($s1)
{ 
 
   return substr($s1, (strlen($s1) - 1) / 2 - 1, 3);

}

echo test("Hello")."\n";
echo test("Python")."\n";
echo test("abc")."\n";

Sample Output:

ell
yth
abc

Flowchart:

PHP Code Editor:

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Previous: Write a PHP program to create a new string of length 2 starting at the given index of a given string.
Next: Write a PHP program to create a new string of length 2, using first two characters of a given string. If the given string length is less than 2 use '#' as missing characters.

What is the difficulty level of this exercise?

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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