PHP Basics for Getting Started (—)

学习 Chapter 1 Welcome to learn about PHP

. First of all, because the products developed by our team are currently entering the financing stage, the first phase of the product development has been completed, and the time is idle. Information, started the learning journey of PHP. I have been reading articles written by other experts on CSDN, and I have learned a lot, which is similar to my personal concept. I think the team must learn to share knowledge, so I will organize my own PHP learning process. Publish it on my personal blog, and everyone is welcome to correct me if I feel it is wrong. Before learning PHP, I had three questions: What is PHP, why should I learn PHP, and how to learn the language PHP?

1.1What is PHP PHP (foreign name: PHP: Hypertext Preprocessor, Chinese name: "Hypertext Preprocessor") is a general open source scripting language. The syntax absorbs the characteristics of C language, Java and Perl, which is easy to learn and widely used. It is mainly suitable for the field of Web development. PHP's unique syntax mixes C, Java, Perl, and PHP's own syntax. It can execute dynamic web pages faster than CGI or Perl. Compared with other programming languages, dynamic pages made with PHP embed programs into HTML (an application under the Standard Universal Markup Language) document for execution, and the execution efficiency is much higher than CGI that completely generates HTML tags; PHP can also execute compiled code. Compilation can achieve encryption and optimize code running, making the code run faster. This is the explanation from Baidu Encyclopedia, which I think can answer my first question.

1.2 Why should you learn PHP The reasons given on the Internet are probably as follows: "I can use JavaScript to write programs." But the ability of JavaScript is limited, and JavaScript usually runs in the browser (client). It can create special effects on web pages: the background changes color when the mouse rolls over it, and the pop-up menu that is common on web pages when the mouse rolls over it. But if you want JavaScript to display "the total number of people who visited the website", it can't do anything, because it can only get the client's information, and the "total number of people who visited the website" is stored on the server side. Therefore, another programming language that can run on the server side is needed, and PHP language is one of them because it can run on the Web server side. But now technology is constantly developing and changing. Now js has been used to write back-end programs, such as node.js, which is very popular recently. Let me write down my personal views here:
(1) First of all, as a newbie entering the programmer industry, learning the PHP programming language can bring us a good income. If you have money, you will have many girls. If you have girls, you will find your love (this paragraph is purely for entertainment).
(2) Secondly, as veterans who have entered the programmer industry, after learning the PHP programming language, we have one more skill. We live in a complex and ever-changing world, especially the mobile Internet, which is ever-changing. We do it for ourselves resume, adding some depth and breadth. As long as I keep working hard to reserve my knowledge base and seize an opportunity, you can successfully achieve your goals.
(3) Interesting students, you can search online for "What are the development languages ​​​​of the top 50 websites in the world". You will find that most websites and the three well-known domestic BAT companies, Sina, 360, etc. have used PHP. It can be concluded that: a. PHP has some characteristics of its own and is recognized by large companies in the Internet industry; b. PHP jobs should be easier to find and pay well because these well-known companies are using it.


1.3 How to learn PHP programming language
(1) First of all, you need the basic syntax of PHP. You must learn and practice while doing more demos (some people here like to read documents and books, and some people like to watch videos, I personally think that you can read documents or books and do exercises. If you don’t understand, you can ask for video explanations or find answers online); Discover your own flaws and strengthen your knowledge point learning;

(3) Then, you can learn relevant framework knowledge, and you will find the benefits of the framework, which can increase your development efficiency.

(4) It is better to use a larger demo to consolidate the knowledge you have learned, and don’t leave it to books in the end. (At the same time, we must strive to persist again, especially for beginners)

Let's get to know PHP and its functions before learning PHP.

1. Running on the server side: Once you learn PHP, you can command the server to do work for you, or even destroy it ^_^ (do not really do this), most of the data of the WEB website is stored in On the server side, PHP is used to process the data stored on the server (it is powerful, right).
： 2. Cross -platform: The server can be a server of multiple platforms, such as Linux, Windows, and UNIX, you can command (don't be afraid to direct one server).

3. Scripting language: It commands the server to work by writing scripts, which are lines of computer instructions (which can also be understood as specific English words). Therefore, the process of writing PHP is actually working with foreigners ( The server is a foreigner) During the communication process, the language of communication is PHP.

4. Free: Free to use (there really is a free lunch in the world). .

1.3 Initial PHP code identification Let’s start with a simple PHP code:

<!DOCTYPE html>
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=utf-8">
<title>欢迎学习php!</title>
</head>
<body>
<p>
<?php 
echo &#39;欢迎进入学习PHP的世界&#39;; 
?></p>
</body>
</html>

Just like you can write JavaScript script language and need to write it between the 3f1c4e4b6b16bbbd69b2ee476dc4f83a2cacc6d41bbb37262a98f745aa00fbf0 tags, You can write PHP code on the page between the 7e03a0c69f50421056697103b83422a0 tags. Echo is the output statement in PHP (anyone who studies Java will think this is very similar to system.out.print()). You can Output the string (enclose the string in double quotes).

A. Use echo for mathematical calculation output

<?php echo 12*3;?>

B． Use echo for string output. Note that connectors can connect multiple strings. The above example is to split a string into two small strings and then connect them with a connector. In PHP, string concatenation is represented by a dot (.), which is quite special. In other languages, it is represented by a plus sign (+), such as:

JavaScirpt、Java、Asp、C。
<?php echo &#39;你好,&#39;.&#39;世界!&#39;;?>

1.4 PHP code comments There are also comment statements in PHP: single-line comments: use double slashes (//) to express, multi-line comments: use /*comment statement*/. In other languages, use db8decba50d102eba7f374374bb9af1b in Html and /*comment statement*/ in CSS. For example, the following code:

<?php
//输出hi,imooc!
echo "hi,imooc!";
?>

Comment statements can be placed anywhere in the PHP program (but the comment statements must be written between bb9bd6d87db7f8730c53cb084e6b4d2d).

The above is the content of the PHP basic learning chapter (—). For more related content, please pay attention to the PHP Chinese website (www.php.cn)!