help me analyzing the code

[penguinprogrammer]

So I was studying overloading operator and case study in the book has this code. Help me analyzing the code. (Ex. what's going to happen on line #)

  ostream &operator<<( ostream &output, const Array &a )
  {
     int i;
     
     // output private ptr-based array
     for ( i = 0; i < a.size; ++i )
     {
        output << setw(12) << a.ptr[i];
        
        if ( ( i + 1 ) % 4 == 0 ) // 4 numbers per row of output
           output << endl;
     }

     if ( i % 4 != 0 ) // end last line of output
        output << endl;

     return output; // enables cout << x << y;
}

[Nico]

http://www.cplusplus.com/reference/ostream/ostream/operator<</

The point of overloading is that you have one function (in this case the << operator) that can be used with arguments from different types.

As for this specific code: this code shows how an Array can be added to a stream. But you should never program this, as it is part of the standard library.

[keskiverto]

But you should never program this, as it is part of the standard library.

Please explain.

That "Array" is some custom type, and the "4 numbers per row of output" is definitely not a standard.


@penguinprogrammer: quite ok, but what makes you think that the "ptr" is array of numbers and private?
What about line 8?