The real power of PHP comes from its functions. There are 1000 built-in functions. You can refer to the PHP reference manual.
Custom function:
<span style="color: #008080;">1</span> <span style="color: #0000ff;">function</span><span style="color: #000000;"> functionName() </span><span style="color: #008080;">2</span> <span style="color: #000000;">{ </span><span style="color: #008080;">3</span> <span style="color: #000000;">要执行的代码; </span><span style="color: #008080;">4</span> }
Guidelines for function naming:
<span style="color: #008080;"> 1</span> <?<span style="color: #000000;">php </span><span style="color: #008080;"> 2</span> <span style="color: #0000ff;">class</span><span style="color: #000000;"> Site { </span><span style="color: #008080;"> 3</span> <span style="color: #008000;">/*</span><span style="color: #008000;"> 成员变量 </span><span style="color: #008000;">*/</span> <span style="color: #008080;"> 4</span> <span style="color: #0000ff;">var</span> <span style="color: #800080;">$url</span><span style="color: #000000;">; </span><span style="color: #008080;"> 5</span> <span style="color: #0000ff;">var</span> <span style="color: #800080;">$title</span><span style="color: #000000;">; </span><span style="color: #008080;"> 6</span> <span style="color: #008080;"> 7</span> <span style="color: #008000;">/*</span><span style="color: #008000;"> 成员函数 </span><span style="color: #008000;">*/</span> <span style="color: #008080;"> 8</span> <span style="color: #0000ff;">function</span> setUrl(<span style="color: #800080;">$par</span><span style="color: #000000;">){ </span><span style="color: #008080;"> 9</span> <span style="color: #800080;">$this</span>->url = <span style="color: #800080;">$par</span><span style="color: #000000;">; </span><span style="color: #008080;">10</span> <span style="color: #000000;"> } </span><span style="color: #008080;">11</span> <span style="color: #008080;">12</span> <span style="color: #0000ff;">function</span><span style="color: #000000;"> getUrl(){ </span><span style="color: #008080;">13</span> <span style="color: #0000ff;">echo</span> <span style="color: #800080;">$this</span>->url . <span style="color: #ff00ff;">PHP_EOL</span><span style="color: #000000;">; </span><span style="color: #008080;">14</span> <span style="color: #000000;"> } </span><span style="color: #008080;">15</span> <span style="color: #008080;">16</span> <span style="color: #0000ff;">function</span> setTitle(<span style="color: #800080;">$par</span><span style="color: #000000;">){ </span><span style="color: #008080;">17</span> <span style="color: #800080;">$this</span>->title = <span style="color: #800080;">$par</span><span style="color: #000000;">; </span><span style="color: #008080;">18</span> <span style="color: #000000;"> } </span><span style="color: #008080;">19</span> <span style="color: #008080;">20</span> <span style="color: #0000ff;">function</span><span style="color: #000000;"> getTitle(){ </span><span style="color: #008080;">21</span> <span style="color: #0000ff;">echo</span> <span style="color: #800080;">$this</span>->title . <span style="color: #ff00ff;">PHP_EOL</span><span style="color: #000000;">; </span><span style="color: #008080;">22</span> <span style="color: #000000;"> } </span><span style="color: #008080;">23</span> <span style="color: #000000;">} </span><span style="color: #008080;">24</span> ?>
The analysis is as follows:
Class uses the class keyword followed by the class name definition.
Variables and methods can be defined within a pair of curly brackets ({}) after the class name.
Class variables are declared using var, and variables can also be initialized.
Function definitions are similar to PHP function definitions, but functions can only be accessedthrough the class and the objects it instantiates.
After the class is created, we can use the new operator to instantiate the object of the class. To access the object members, use -> access, no longer., use new Site to call the no-argument constructor without parentheses :
<span style="color: #008080;">1</span> <span style="color: #800080;">$runoob</span> = <span style="color: #0000ff;">new</span><span style="color: #000000;"> Site; </span><span style="color: #008080;">2</span> <span style="color: #800080;">$taobao</span> = <span style="color: #0000ff;">new</span><span style="color: #000000;"> Site; </span><span style="color: #008080;">3</span> <span style="color: #800080;">$google</span> = <span style="color: #0000ff;">new</span> Site;
<span style="color: #008080;">1</span> <span style="color: #800080;">$runoob</span>->setTitle( "菜鸟教程" );
Use _construct to name the constructor
<span style="color: #008080;">1</span> <span style="color: #0000ff;">function</span> __construct( <span style="color: #800080;">$par1</span>, <span style="color: #800080;">$par2</span><span style="color: #000000;"> ) { </span><span style="color: #008080;">2</span> <span style="color: #800080;">$this</span>->url = <span style="color: #800080;">$par1</span><span style="color: #000000;">; </span><span style="color: #008080;">3</span> <span style="color: #800080;">$this</span>->title = <span style="color: #800080;">$par2</span><span style="color: #000000;">; </span><span style="color: #008080;">4</span> }
Contrary to the constructor, when the object ends its life cycle (for example, the function in which the object is located has been called), the system automatically executes the destructor
<span style="color: #008080;"> 1</span> <?<span style="color: #000000;">php </span><span style="color: #008080;"> 2</span> <span style="color: #0000ff;">class</span><span style="color: #000000;"> MyDestructableClass { </span><span style="color: #008080;"> 3</span> <span style="color: #0000ff;">function</span><span style="color: #000000;"> __construct() { </span><span style="color: #008080;"> 4</span> <span style="color: #0000ff;">print</span> "构造函数\n"<span style="color: #000000;">; </span><span style="color: #008080;"> 5</span> <span style="color: #800080;">$this</span>->name = "MyDestructableClass"<span style="color: #000000;">; </span><span style="color: #008080;"> 6</span> <span style="color: #000000;"> } </span><span style="color: #008080;"> 7</span> <span style="color: #008080;"> 8</span> <span style="color: #0000ff;">function</span><span style="color: #000000;"> __destruct() { </span><span style="color: #008080;"> 9</span> <span style="color: #0000ff;">print</span> "销毁 " . <span style="color: #800080;">$this</span>->name . "\n"<span style="color: #000000;">; </span><span style="color: #008080;">10</span> <span style="color: #000000;"> } </span><span style="color: #008080;">11</span> <span style="color: #000000;">} </span><span style="color: #008080;">12</span> <span style="color: #008080;">13</span> <span style="color: #800080;">$obj</span> = <span style="color: #0000ff;">new</span><span style="color: #000000;"> MyDestructableClass(); </span><span style="color: #008080;">14</span> ?>
The execution result is:
<span style="color: #000000;">构造函数 销毁 MyDestructableClass</span>
Single root inheritance, inheritance uses the keyword extends, and interface implementation uses implements
OK, you have finished learning PHP functions and objects. Note that this tutorial is a quick learning tutorial and only focuses on some grammatical key points and special and different points.