The simplest formula to calculate page count?

Question

I have an array and I want to divide them into page according to preset page size.

This is how I do:

private int CalcPagesCount()
{
    int  totalPage = imagesFound.Length / PageSize;

    // add the last page, ugly
    if (imagesFound.Length % PageSize != 0) totalPage++;
    return totalPage;
}

I feel the calculation is not the simplest (I am poor in math), can you give one simpler calculation formula?

Answer 1

Force it to round up:

totalPage = (imagesFound.Length + PageSize - 1) / PageSize;

Or use floating point math:

totalPage = (int) Math.Ceiling((double) imagesFound.Length / PageSize);

Answer 2

Actually, you are close to the best you can do. About the only thing that I can think of that might be "better" is something like this:

totalPage = (imagesFound.Length + PageSize - 1) / PageSize;

And the only reason that this is any better is that you avoid the if statement.

Answer 3

NOTE: you will always get at least 1 page, even for 0 count, if the page size is > 1, which is what I needed but may not be what you need. A page size of 1(silly but technically valid) and a count of 0 would be zero pages. Depending on your needs you may want to check for a zero value for count & page size of 1

int pages = ((count - 1) / PAGESIZE) + 1;

Answer 4

The OP contains a valid answer. If I wanted to turn off paging then I could set PageSize = int.MaxValue.

Several answers here add to PageSize (imagesFound.Length + PageSize) and that would cause an overflow. Which then leads to an incorrect result.

This is the code I am going to use:

int imageCount = imagesFound.Length;

// include this if when you always want at least 1 page 
if (imageCount == 0)
{
    return 1;
}

return imageCount % PageSize != 0 
    ? imageCount / PageSize + 1 
    : imageCount / PageSize;

Answer 5

To avoid having errors with page numbering the best way I can think of calculating noOfPages is by doing the following line

totalPage = Math.Ceiling(imagesFound.Length / PageSize);

This should not give you page 2 when PageSize == imagesFound.Length