PHP function learning experience

Recently, I have browsed PHP functions in a more detailed manner. I didn't feel much when I did not read them before, but now I have discovered that if I really want to understand all the functions of PHP, i'm afraid it's never a cold day! Although PHP does not provide the most abundant functions, it also has a very large number of functions, while SyntaxHighlighter. all ();

Recently, I have browsed PHP functions in a more detailed manner. I didn't feel much when I did not read them before, but now I have discovered that if I really want to understand all the functions of PHP, i'm afraid it's never a cold day! Although PHP does not provide the most abundant functions, it also has a very large number of functions and a wide range of functions, in addition to PHP knowledge, it also requires a lot of related network knowledge. But if you really have the patience to conquer every function one by one, I believe that you will certainly benefit a lot.
Well, the following is my learning experience and summary. I will discuss it with you. I wonder if it will help you learn it!
Currently, PHP4 is used as the standard. The latest online manual contains 76 types of function libraries, with different numbers of specific functions in each category. When I came up with so many functions, I couldn't understand them! Slowly, for the convenience of learning, I divided these functions into the following categories:
1. common PHP functions: these functions should basically be available after you install PHP by default. you can use them immediately, including mathematical functions and string functions, similar functions are available in many other languages. if you have some programming experience, it is not difficult to learn them.
2. functions for interacting with the database management system: anyone who has read the preface of the PHP manual should know that PHP supports a large number of database systems, PHP interacts with these database systems through a batch of functions. Although PHP supports many databases, the methods for operating databases through PHP are basically the same, and the programming logic is similar. So you can choose one of them based on your own situation. after learning one, other function libraries will basically be mastered. of course, there may be some slight differences, however, I have some experience with the first type of database. The rest should be fine for you.
3. extended or very useful functions: these functions are classified into two types: one is supported only when related compilation options are included in PHP compilation. The other is designed to support products of other companies, so if you want to use it, you also need related product support and knowledge.
Through the above classification, I think we should follow the above classification order when learning, first master all the basic operation functions, they may also be used in your future study. This part should not be very difficult, and they will give you confidence to continue to learn! Then I will study the database function library. the implementation of dynamic web pages depends largely on the application of the database system. If PHP is not used to control the database, I can only say that you have not learned PHP. So how should we do so many functions? One of them is selected. due to the absolute combination of MySQL and PHP, I think you should start with it and you can continue learning in the windows environment, why not? Finally, I will study the third type of functions. of course, you may not need to learn them because these functions are generally used to solve special problems. If you want to learn it, no one will stop you. However, when learning this function, I am afraid you still need a lot of other related knowledge, such as Linux and XML. Only in this case can you really understand what you are doing, how should you debug your program, and analyze whether your program is correctly executed.

The last point is very important: when learning functions, it is best to manually compile small programs and verify the functions of the functions, so that you can remember deeply. The learning effect should be better.
Well, the above is my experience in the course of learning. below is what I think should belong to the first type of function in the course of learning. you will know the database function at first glance, I don't need to talk about it. The rest should belong to the third category! For your reference only, please kindly advise!
Common PHP functions:
Array, Date/Time, Directory, Error and Logging, FileSystem, FTP, HTTP, Mail, Math, Network, PHP Option, Regexps, Session, String, URL, Variable