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PHP Exercises: Create a new string of the characters at indexes 0,1,4,5,8,9 ... from a given string

PHP Basic Algorithm: Exercise-36 with Solution

Write a PHP program to create a new string of the characters at indexes 0,1,4,5,8,9 ... from a given string.

Sample Solution:

PHP Code :

<?php
function test($s)
{
          $result = "";
            for ($i = 0; $i < strlen($s); $i=$i+4)
            {
                $c = $i + 2;
                $n = 0;
                $z = $c > strlen($s) ? 1 : 2;
                $n = $n + $z;
                $result = $result.substr($s, $i, $n);
            }
            return $result;
 }

echo (test("Python"))."\n";
echo (test("JavaScript"))."\n";
echo (test("HTML"))."\n";

Sample Output:

Pyon
JaScpt
HT

Pictorial Presentation:

PHP Basic Algorithm Exercises: Create a new string of the characters at indexes 0,1,4,5,8,9 ... from a given string.

Flowchart:

Flowchart: Create a new string of the characters at indexes 0,1,4,5,8,9 ... from a given string.

PHP Code Editor:

Contribute your code and comments through Disqus.

Previous: Write a PHP program to compare two given strings and return the number of the positions where they contain the same length 2 substring.
Next: Write a PHP program to count the number of two 5's are next to each other in an array of integers. Also count the situation where the second 5 is actually a 6.

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