This code in the c + + primer is a little not understand

 
The class Screen 
{
Public: 
/* typedef STD: : string: : size_type pos. 
Screen & amp; The set (char); 
Screen & amp; Set (pos, pos, char); 
Screen ()=default; 
Screen (pos ht, pos wd, char c) : height (ht), width (wd), contents (ht * wd, c) {} */
Screen & amp; The display (STD: : ostream & amp; OS) 
{
Do_display (OS); 
Return * this; 
} 
Const Screen & amp; The display (STD: : ostream & amp; OS) const 
{
Do_display (OS); 
Return * this; 
} 
/* char the get () const 
{
Return contents (cursor); 
} 
Char get (pos ht, pos wd) const; 
Screen & amp; Move (pos r, pos c); */
Private: 
/* pos cursor=0; 
Pos height=0, width=0; */
STD: : string contents; 
Void do_display (STD: : ostream & amp; OS) const {OS & lt; }; 
//... 
//the main () {
Const Screen blank (5, 3); 
Blank. The display (cout); 
//} 

Class is how to determine blank is const, then let him call const version of the display? Personal feeling is because the implicit parameter blank this type is const Screen * const, so at the time of overloaded function called discovery and const version of the display to match better, so call const version of the display? Understand it right?

CodePudding user response:

Compile time will know