PHP program to print an arithmetic progression series using inbuilt functions

We have to print an arithmetic progressive series in PHP, between two given numbers a and b both including, a given common arithmetic difference of d. 

Examples:

Input : $a = 200, $b = 250, $d = 10
Output : 200, 210, 220, 230, 240, 250

Input : $a = 10, $b = 100, $d = 20
Output : 10, 30, 50, 70, 90

This problem can be solved using loops by iterating from $a to $b and incrementing the loop variable by $d. But in PHP we can also make use of some inbuilt functions to solve this particular problem. We will have to use the below two functions for this purpose:

• range() function: This function is used to create an array of elements of any kind such as integers, or alphabets within a given range(from low to high) i.e, list’s first element is considered as low and the last one is considered as high.
• implode() function: If we have an array of elements, we can use the implode() function to join them all to form one string. We basically join array elements with a string.

The idea to solve this problem using the above two inbuilt functions is to first use the range() function to generate an array of values between $a and $b where the values are incremented by $d. After generating the array we will use the implode() function to create a string from the array where elements will be separated by a comma(,) separator. 

PHP

<?php

$a = 1;
$b = 100;
$d = 15;

$arr = range($a,$b,$d);

echo implode(", ",$arr);

?>

Output:

1, 16, 31, 46, 61, 76, 91

Time complexity: O(n) // To print series up to nth tern

Auxiliary Space: O(1)