PHP: Detailed explanation, paging through process-oriented

　　　　Premise: Create a database, preferably with more than 20 pieces of data in the database, so that we can realize the paging effect achieved in different situations

 　　　　

　　　　We set a page, only 9 page buttons can appear at the same time, the middle value is 5

　　　　Paging is divided into three scenarios:

　　　　(1) Scenario 1: When the current number of pages is less than 5 or the total number of pages is less than or equal to 9, the 1-9 page button is displayed

　　　　(2) Scenario 2: When the current page is greater than or equal to 5, and the current page plus 5 is less than or equal to the total number of pages, the first 4 and last 4 pages of the current page are displayed

　　　　(3) Scenario 3: The current page number is greater than 9

 

 

　　　　Effect:

　　

 

　　

 

 

 

 

　　Code: Looking at the code by the number of lines, I annotated the meaning and logic of almost every sentence of the code. If you read it carefully, you will be able to understand the entire running process.

　　

 

 

　　　　above

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