php what is interface

PHP Interface

##Using interface (interface), you can specify which methods a certain class must implement , but the specific content of these methods does not need to be defined.

The interface is defined through the interface keyword, just like defining a standard class, but all methods defined in it are empty.

All methods defined in the interface must be public. This is a characteristic of the interface. (Recommended learning: PHP programming from entry to proficiency)

Implementation (implements)

To implement an interface, use the implements operation symbol. The class must implement all methods defined in the interface, otherwise a fatal error will be reported. A class can implement multiple interfaces. Use commas to separate the names of multiple interfaces.

Note:

When implementing multiple interfaces, methods in the interfaces cannot have the same name.

Note:

Interfaces can also be inherited, by using the extends operator.

Note:

To implement an interface, a class must use the method that is exactly the same as the method defined in the interface. Otherwise a fatal error will result.

Interface instance

<?php

// 声明一个&#39;iTemplate&#39;接口
interface iTemplate
{
    public function setVariable($name, $var);
    public function getHtml($template);
}
// 实现接口
// 下面的写法是正确的
class Template implements iTemplate
{
    private $vars = array();
  
    public function setVariable($name, $var)
    {
        $this->vars[$name] = $var;
    }
  
    public function getHtml($template)
    {
        foreach($this->vars as $name => $value) {
            $template = str_replace(&#39;{&#39; . $name . &#39;}&#39;, $value, $template);
        }
 
        return $template;
    }
}
// 下面的写法是错误的，会报错，因为没有实现 getHtml()：
// Fatal error: Class BadTemplate contains 1 abstract methods
// and must therefore be declared abstract (iTemplate::getHtml)
class BadTemplate implements iTemplate
{
    private $vars = array();
    public function setVariable($name, $var)
    {
        $this->vars[$name] = $var;
    }
}
?>

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