使用$ variable ++的数学获取页码并计算起始编号

Question

this is more of a maths question than anything but still related.

So,

I have a basic cms that displays 4 blog posts on each page. The page number is in the url so i can get that.

I am trying to number the results using $variable++ in a foreach loop however that of course resets back to 1 when the new page is loaded.

Example for page 1:

$postNumber = 1;

foreach:
  echo "$postNumber";
  $postNumber++;
endforeach;

Now the issue comes when going to page 2.

I need to come up with a way to take the page number and then create the next set of post numbers.

So the post numbers / page numbers needed would be:

Page Number / Post start number
1 / 1
2 / 5
3 / 9
4 / 13
5 / 17
6 / 21
7 / 25
etc

The gap in between each page number / post numbers increases by 3 every time (0,3,6,9,12,15 etc)

Maths isn't my strong points, or maybe because its late... but i cant figure out a way to do this. Make sense?

Answer 1

Your post numbers are increased by 4 every page:

$postNumber = 1;
$pageNumber = 1;

foreach:
    echo $pageNumber, '/', $postNumber;
    $postNumber += 4;
    ++$pageNumber;
endforeach;