Difference between double colon and arrow operators?

05/15/2020 16:30:01

In the sidebar of the php web manual, link text the addChild method uses the :: scope resolution operator, but in the example it uses the Arrow operator. Can anyone tell me why that is?

Verified Answer (115 Votes)

10/18/2010 22:07:47

:: is for static elements while -> is for instance elements.

For example:

class Example {
  public static function hello(){
    echo 'hello';
  }
  public function world(){
    echo 'world';
  }
}

// Static method, can be called from the class name
Example::hello();

// Instance method, can only be called from an instance of the class
$obj = new Example();
$obj->world();

More about the static concept

115

Answer #2 (4 Votes)

10/18/2010 22:04:37

This is just notation for the fact that its the method of an object and has nothing to do with actual usage.

In the case of documentation youre not dealing with an instance of an object like $object so the -> operator wouldnt be correct since you want to list the actual class name. So following the usage for a static method where the class name is static you use the scope res. operator ::...

This is generally how php documentation works for classes.

4

Answer #3 (3 Votes)

10/18/2010 22:06:38

The arrow means the addChild is called as a member of the object (in this case $sxe).

The double colon means that addChild is a member of the SimpleXMLElement class.

3
3
Hack Hex uses Stack Exchance API by the Stack Exchange Inc. to scrape questions/answers under Creative Commons license.