PHP Challenges: Check whether a sequence of numbers is an arithmetic progression or not
PHP Challenges - 1: Exercise-15 with Solution
Write a PHP program to check whether a sequence of numbers is an arithmetic progression or not.
Input : array(5, 7, 9, 11)
In mathematics, an arithmetic progression or arithmetic sequence is a sequence of numbers such that the difference between the consecutive terms is constant.
For example, the sequence 5, 7, 9, 11, 13, 15 ... is an arithmetic progression with common difference of 2.
Explanation :
Sample Solution :
PHP Code :
<?php
function is_arithmetic($arr)
{
$delta = $arr[1] - $arr[0];
for($index=0; $index<sizeof($arr)-1; $index++)
{
if (($arr[$index + 1] - $arr[$index]) != $delta)
{
return "Not an arithmetic sequence";
}
}
return "An arithmetic sequence";
}
$my_arr1 = array(6, 7, 9, 11);
$my_arr2 = array(5, 7, 9, 11);
print_r(is_arithmetic($my_arr1)."\n");
print_r(is_arithmetic($my_arr2)."\n");
?>
Sample Output:
Not an arithmetic sequence An arithmetic sequence
Flowchart:
PHP Code Editor:
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Previous: Write a PHP program to reverse the bits of an integer (32 bits unsigned).
Next: Write a PHP program to check whether a sequence of numbers is a geometric progression or not.
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PHP: Tips of the Day
How to Sort Multi-dimensional Array by Value?
Try a usort, If you are still on PHP 5.2 or earlier, you'll have to define a sorting function first:
Example:
function sortByOrder($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
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