Why is there a negative number in php array pagination?

For PHP developers, array paging is a common requirement. But sometimes, when we implement array paging, we encounter negative numbers. This article will discuss the reasons why this happens and how to fix it.

1. Reasons for negative numbers

1. Array subscripts start from 0

In PHP, array subscripts start counting from 0. When we use functions like array_slice to perform array paging, we need to pay attention to the value of the starting subscript. If the value is less than 0, a negative number will appear.

2. The paging size is unreasonable

When performing array paging, we need to specify the number of elements displayed on each page. If the paging size is not handled properly, the number of elements on the last page will not be enough, resulting in a negative number.

3. The total number of elements is unreasonable

The unreasonable number of total elements will also lead to negative numbers. For example, a negative number occurs when the total number of elements is less than or equal to the page size.

2. Solution

1. Specify the starting subscript

In order to avoid negative numbers, we need to specify the starting subscript before paging the array. You can use PHP's max function to limit the subscript to 0.

For example:

$start = max($currentPage - 1, 0) * $pageSize;
$pageData = array_slice($data, $start, $pageSize);

2. Handling paging size

When handling paging size, we need to pay attention to ensure that the number of elements on the last page is not less than 0. If the number of elements on the last page is less than 0, you need to limit the paging size to the total number of elements.

For example:

$pageSize = 10;
$total = count($data);
$maxPage = ceil($total / $pageSize);
if ($currentPage > $maxPage) {

$currentPage = $maxPage;

}
$start = ($currentPage - 1) * $pageSize;
$pageData = array_slice($data, $start, $pageSize) ;

3. Processing the total number of elements

When processing the total number of elements, we need to ensure that the total number of elements is not less than the paging size. If the total number of elements is less than the page size, you need to limit the page size to the total number of elements.

For example:

$pageSize = 10;
$total = count($data);
if ($total < $pageSize) {

$pageSize = $total;

}
$maxPage = ceil($total / $pageSize);
$start = ($currentPage - 1) * $pageSize;
$pageData = array_slice($data, $start, $pageSize) ;

3. Summary

Array paging is a basic skill in PHP development. However, negative numbers are also a common problem. When dealing with array paging, you need to pay attention to the value of the array subscript, the processing of paging size, and the limit on the total number of elements to avoid negative numbers. Hope this article is helpful to you.

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