PHP static methods and properties

class hw
{
	public static function hi()
	{
		return 'Hello World';
	}
}
echo hw::hi();//Output:Hellp World

class hw2
{
	public function hi()
	{
		return 'Hello Wrold';
	}
}
echo hw2::hi();//Output:Hellp World

As can be seen from the above example, after using the static attribute or not using the static attribute, you can directly use the :: method to call it directly from the outside. However, for efficiency and other reasons, it is recommended to use static restrictions.

Calling methods within a static class

class foo
{
    private static function c()
    {
        return 'abcde';
    }

    public static function a()
    {
        echo self::c();
    }

    public static function b()
    {
        echo $this->c();
    }

    public function  e()
    {
        echo self::c();
    }
}
foo::a();//Output:abcde
foo::b();//Output:Fatal error: Using $this when not in object context in
foo::e();//Output:abcef

Methods restricted using the static keyword must be referenced within this class using self::.

static attribute

class foo
{
	public static $a;
	public static function a()
	{
		self::$a = 'abcd';
	}
}
foo::a();//Output:abcde
echo foo::$a;

static inheritance and use

class foo
{
	public static $a;
	public static function a()
	{
		return 'abcde';
	}
}

class soo extends foo
{
	public static function a()
	{
		echo '12345';
	}
}

soo::a();//Output:12345

static inheritance is the same as the inheritance method of ordinary classes, and there is not much difference.

class foo
{
	public static $a;
	public static function a()
	{
		return 'abcde';
	}
}

class soo extends foo
{
	public static function a()
	{
		echo parent::a();
	}
}

soo::a();//Output:12345

There is only a writing difference when using it. It must be the parent:: method to reference the method of the parent class, and the method cannot be used directly by self::, otherwise there will be no output:

class foo
{
	public static $a;
	public static function a()
	{
		return 'abcd';
	}
}
 
class soo extends foo
{
	public static  function aa()
	{
		echo self::a();
	}
}
soo::a();  

The above introduces PHP static methods and attributes, including aspects of content. I hope it will be helpful to friends who are interested in PHP tutorials.