How should i code this paging?

I've been struggling with some code for a paging for a couple of days (YES! days) now but can't get it to work properly, probably because I don't have any experience on this kind of problems yet.

the paging I'm trying to do should look something like this:

1 2 3 4 5 6 ... 101

When i click on number 5 i would like it to display the numbers like this:

1 ... 3 4 5 6 7 ... 101

when I'm at the last couple of pages i want it to look similar to the first one:

1 ... 96 97 98 99 100 101

The bold number is the page that you're currently viewing.

I want the dots to appear only when there is more than 7 pages available, if not it should look like a normal paging would look like:

1 2 3 4 5 6 7

Right now i want to display 10 items per page.

The lang开发者_JAVA技巧uage i want to use is C# (ASP.NET) and would like to, later on make this a usercontrol (Where i should set the properties TotalNumberOfItems, ItemsPerPage and so on).

The question: How do i write the code to loop out the numbers on the correct places? :)

How about (Make it Bold is somewhat psuedoCode cause I don't know what UI you're in...)

   private static string BuildPaging(int pageNo, int pageCount)
   {
      StringBuilder sb = new StringBuilder();

      for(int i = 1; i < pageCount; i++)
      {
         if (i == pageNo) 
             sb.Append([Make it Bold] + i.ToString("0") + [Make it not Bold]);
         else if (1 > pageNo - 3 && i < pageNo + 3)
             sb.Append(i.ToString("0"));
         else if ((i == 2 && pageNo > 4) ||        
                  (i == PageCount - 1 && pageNo < PageCount - 2))
             sb.Append("...");
      }
      return sb.ToString();
   }

Only thing is how to make it bold (Depends on whether you're in WinForms or ASP.Net... ... And add stuff to make it a clickable link...

You need maximum pager inner list size (those between dots), page size, documents counter and current page index. Then you can use algorithm like this:

_pagesTotal = DocumentsTotal / DocumentsPerPage;
if ( DocumentsTotal % DocumentsPerPage > 0 )
{
    _pagesTotal++;
}
// we want current page in the middle
// PageBlockMaxSize is the size of those dotted out pages
int halfBlock = PageBlockMaxSize / 2;
if ( CurrentPageIndex > PageBlockMaxSize )
{
    // add some code here to show first page link and following dots
    // ...    
    _firstPageInBlockIndex = CurrentPageIndex - halfBlock;
}
else
{
    // we don't need any dots here
_firstPageInBlockIndex = 1;
}

if ( _pagesTotal - CurrentPageIndex > PageBlockMaxSize )
{
    // here show last page link and preceeding dots. you can use _pagesTotal as it's text
    // ...    
    _lastPageInBlockIndex = CurrentPageIndex + halfBlock;
}
else
{
    // we don't need any dots here
    _lastPageInBlockIndex = _pagesTotal;
}

// hide next-previous buttons if they are not needed
if ( CurrentPageIndex == 1 )
{
    spanPrev.Visible = false;
}
else if ( CurrentPageIndex == _pagesTotal )
{
    spanNext.Visible = false;
}

// and when we are ready we build list of page counters
var pages = new List<int>();
for ( int page = _firstPageInBlockIndex;
      page <= _lastPageInBlockIndex;
      page++ )
{
    pages.Add( page );
}

and then we can databind this list to some repeater or use it some other way to display common links between those dots (or without them).

I've done something like that. It has a few that are different from what you want exactly, but should be helpful. This was a quick and dirty solution to a problem and has a number of efficiency issues, but it's a good start.

public class PagingHelper
{
    public IEnumerable<int> GetListOfPages(int currentPage, int pagesAroundCurrent, int totalPages)
    {
        var pages = new Dictionary<int, int>();
        double powerOfTenTotalPages = Math.Floor(Math.Log10(totalPages));
        if ((int)powerOfTenTotalPages == 0)
        {
            powerOfTenTotalPages = 1;
        }
        pages.Add(1, 1);
        if (!pages.ContainsKey(totalPages))
        {
            pages.Add(totalPages, totalPages);
        }

        for (int loop = 1; loop <= powerOfTenTotalPages + 1; loop++)
        {
            GetPages(pages, currentPage, pagesAroundCurrent, totalPages, (int)Math.Pow(10, loop - 1));
        }
        return pages.OrderBy(k=>k.Key).Select(p=>p.Key).AsEnumerable();
    }

    private void GetPages(Dictionary<int, int> pages, int currentPage, int pagesAroundCurrent, int totalPages, int jump)
    {
        int startPage = ((currentPage / jump) * jump) - (pagesAroundCurrent * jump);

        if (startPage < 0)
        {
            startPage = 0;
            pagesAroundCurrent = 10;
        }

        int endPage = currentPage + (pagesAroundCurrent * jump);
        if (endPage > totalPages)
        {
            endPage = totalPages;
        }
        AddPagesToDict(pages, startPage, endPage, jump);
    }

    private void AddPagesToDict(Dictionary<int, int> pages, int start, int end, int jump)
    {
        for (int loop = start; loop <= end; loop += jump)
        {
            if (!pages.ContainsKey(loop))
            {
                if (loop > 0)
                {
                    pages.Add(loop, loop);
                }
            }
        }
    }
}

Sample output -

Current Page:1 Total Pages:40 Pages to display around current page:5

1 2 3 4 5 6 7 8 9 10 11 20 30 40

Current Page:90 Total Pages:600 Pages to display around current page:5

1 40 50 60 70 80 85 86 87 88 89 90 91 92 93 94 95 100 110 120 130 140 200 300 400 500 600

Current Page:147 Total Pages:6825 Pages to display around current page:5

For full details see a post here.