Basic introduction to xml and xml tag elements for getting started with php operation xml

The example of this article describes the basic introduction of XML and XML tag elements for getting started with PHP operation of XML. Share it with everyone for your reference. The specific analysis is as follows:

Explain with xml examples:

<?xml version="1.0" encoding="utf-8" standalone="no" ?>
<class>
 <student>
  <name>小乔</name>
  <sex>女</sex>
  <age>23</age>
 </student>
 <student>
  <name>周瑜</name>
  <sex>男</sex>
  <age>27</age>
 </student>
</class>

1. xml statement:

(1). The xml statement should be placed on the first line of the document;
(2) Encoding: document character encoding, such as utf-8, gb2312, etc.
(3), standalone: ​​The value is yes or no, optional, indicating whether the document definition is independent, that is, whether it is related to other documents. The default is no.

2. Root element

The outermost is the root element. Each xml document must have and can only have one root element.

3. xml elements/tags/nodes

, , , > ; and so on are elements of xml, and elements are also called labels or nodes. Of course, the root element is also an element.
If there is no content in the tag, such as there is no entity content between , it can be abbreviated as . Even if it is written as , when the browser is opened, it will still display

4. Spaces and line breaks in tags

Spaces and line breaks that appear in tags, the xml document will Spaces and newlines are treated as original content. So, pay special attention when programming.

5. Naming specifications for xml tags

(1) case-sensitive;
(2) cannot start with numbers or "_";
(3) cannot start with special characters such as xml, XML, Xml, etc.;
(4 ) cannot contain spaces;
(5) cannot contain colons.

I hope what is described in this article will be helpful to everyone’s php operation XML programming.

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