About PHP namespaces (combined with code examples, simple and easy to understand)

here is the name of the PHP I have to organize the namespace, interested students can go to see.

First file
cat.class.php

<?phpnamespace Animals\cat;        Class Cat    {public            function speak ()            {                    echo ' miaow ';            }    }        function root ()    {                return ' cat.class.php ';    }? >123456789101112131415

A second file
dog.class.php

<?phpnamespace Animals\dog;        Class Dog    {public        function speak ()        {            echo ' woof ';        }    }    Class Cat    {public        function speak ()        {            echo ' Miaoth ';        }    }    function root () {        return ' dog.class.php ';    }? >1234567891011121314151617181920212223

index.php
A third file, the file that loads the above namespace

<?php namespace Index;        Require_once ' cat.class.php ';        Require_once ' dog.class.php ';        Use Animals\cat;            Use Animals\dog as Snoopi;      Fully qualified name $cat 1 = new \animals\cat\cat ();        $cat 1->speak ();        Echo ' <br/> ';        $cat 2 = new \animals\dog\cat ();        $cat 2->speak ();        Echo ' <br/> ';        $dog 1 = new \animals\dog\dog ();        $dog 1->speak ();            Echo ' <br/> ';        The non-fully qualified name $cat 3 = new Cat\cat ();        $cat 3->speak ();            Echo ' <br/> ';        Aliases * Aliases and non-fully qualified names cannot be used together $dog 3 = new Snoopi\dog ();        $dog 3->speak ();        More than just functions, any available resource under the namespace can invoke [functions, variables, constants, and so on] echo snoopi\root (); Echo ' <br/> ';? >12345678910111213141516171819202122232425262728293031323334 

Namespace classes can be analogous to file directory systems
A class [or function, variable, etc.] of a namespace invokes the contents of a file in a directory
The fully qualified name is the office to find the contents of the file in the path
A non-fully qualified name is equivalent to
Use the ' relative path ' assignment to a variable when using the namespace, which defaults to the last sub-space
Use the AS keyword to set the name of the variable, which is the alias, so aliases and non-fully qualified names cannot be used at the same time (because a use[+as] can only have one alias).
Analogy file directory system:
File location:/root/path/file/filecontent;
Use/root/path/file is file= '/root/path/file′ so the path to file is file= '/root/path/file′ so the path to file is File/filecontent
* Namespace Index in index.php, equivalent to indicating the current file location
So if the contents of the file in the index.php are modified to

<?php    require_once ' cat.class.php ';        Require_once ' dog.class.php ';        Use Animals\cat\cat; #引入该命名空间下的类    $cat 4 = new Cat ();        $cat 4->speak ();    Root ();? >123456789

Use is equivalent to loading only the cat class in the namespace Animals\cat, and the root () function does not ' load '
So the run will hold an error: the root () function is not declared

Above is the namespace I have compiled for you about PHP, I hope it will be helpful to everyone in the future.

Related articles:

PHP namespaces (combined with code detailed answers)

Learn more about the difference between PHP namespaces and automatic loading

To detail the scope in PHP in conjunction with code