We have to print an arithmetic progressive series in PHP, between two given numbers *a* and *b* both including, with 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 integer, alphabets within a given range(from low to high) i.e, list’s first element is considered as low and 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 comma(,) separator.

`<?php ` ` ` `$a` `= 1; ` `$b` `= 100; ` `$d` `= 15; ` ` ` `$arr` `= range(` `$a` `,` `$b` `,` `$d` `); ` ` ` `echo` `implode(` `", "` `,` `$arr` `); ` ` ` `?> ` |

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Output:

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