PHP functions - Exercises, Practice, Solution

Last update on May 30 2022 11:42:04 (UTC/GMT +8 hours)

PHP functions [ 6 exercises with solution]

1. Write a function to calculate the factorial of a number (a non-negative integer). The function accepts the number as an argument. Go to the editor

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2. Write a function to check whether a number is prime or not. Go to the editor
Note: A prime number (or a prime) is a natural number greater than 1 that has no positive divisors other than 1 and itself.

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3. Write a function to reverse a string. Go to the editor

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4. Write a function to sort an array. Go to the editor

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5. Write a PHP function that checks whether a string is all lowercase. Go to the editor
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6. Write a PHP function that checks whether a passed string is a palindrome or not? Go to the editor
A palindrome is a word, phrase, or sequence that reads the same backward as forward, e.g., madam or nurses run.

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PHP Code Editor:

More to Come !

Do not submit any solution of the above exercises at here, if you want to contribute go to the appropriate exercise page.

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