How Many Pages Do I Need for Pagination: Solving the Integer Division Problem?

Rounding Up Integer Division: A Pagination Enigma

In the realm of programming, integer division often presents a dilemma when dealing with pagination scenarios. Consider a scenario where you have a collection of items that you want to display in fixed-size pages. How do you determine the total number of pages needed?

While it may seem like a straightforward calculation, integer division truncates the result, leading to incorrect pagination controls. For instance, if you have 11 items that you want to display in pages of 3, integer division would give you 3, indicating only 3 pages. However, we know that you actually need 4 pages to display all the items.

To address this problem, we need to round up the result of integer division. One elegant solution was discovered in Roland Backhouse's 2001 book "Number Conversion":

int pageCount = (records + recordsPerPage - 1) / recordsPerPage;

This formula ensures that the result is always rounded up to the nearest integer, providing the correct number of pages needed for pagination. By adding "- 1" to the numerator and dividing by the page size, we effectively drop any remainder, giving us the total number of pages.

Utilizing this formula in programming languages like C# or Java enables you to display accurate pagination controls, ensuring that all items are accounted for and displayed properly.

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