Could someone explain some code?

[E. Robert Tisdale]

Re: Could someone explain some code?

Gactimus wrote:
[color=blue]
> Can anyone explain what the lines with the '*' by them do?
>
> -----------
>
> #ifndef GUARD_COUNTER_H
> #define GUARD_COUNTER_H 1
> #include <iostream>
> // using namespace std;
>
> class Counter {
> private:
> int count;
> public:
> Counter(void): count(0) { } // default constructor
> Counter& operator++(void ) { ++count; return *this; }
> int GetCount(void) { return count; }
> Counter& SetCount(int c) { count = c;[/color]
return *this; }
friend
std::ostream& operator<<(std: :ostream& os, const Counter& c) {
return os << c.count;
}[color=blue]
> // void PrintCount() { cout << "\n The count is " << count; }
>
> };
>
> class NewCounter: public Counter {
> public:
> NewCounter& operator--(void) { --count; return *this; }
> };
>
> #endif//GUARD_COUNTER_H[/color]

[Gactimus]

Re: Could someone explain some code?

Gactimus <gactimus@xrs.n et> wrote in
news:1102605878 .0eb1675083e856 48bb700b5e41f13 861@bubbanews:
[color=blue]
> Can anyone explain what the lines with the '*' by them do?
>
> -----------
>
> #ifndef _COUNTER_H
> #define _COUNTER_H
> #include <iostream>
> using namespace std;
>
> class Counter
> {
> public:
> int count;[/color]




[color=blue]
> public:
> * Counter(){count = 0;}
> void operator ++() { ++count; }
> int GetCount() { return count; }
> void SetCount( int c ) { count = c; }
> void PrintCount() { cout << "\n The count is " << count; }[/color]

If this section was protected, how would one access it using a friend?

[color=blue]
> };
>
> class NewCounter:publ ic Counter
> {
> public:
> * void operator --() { --count; }
> };
>
> #endif[/color]

[David White]

Re: Could someone explain some code?

"Gactimus" <gactimus@xrs.n et> wrote in message
news:1102623238 .bb85af6c6bc249 3985259870e2129 90a@bubbanews.. .[color=blue]
> Victor Bazarov <v.Abazarov@com Acast.net> wrote in
> news:3r2ud.1206 2$Ae.5897@newsr ead1.dllstx09.u s.to.verio.net:[color=green]
> > It's called "the body of the function".[/color]
>
> So is it just a more efficient way of writing a function instead of
> writing a prototype and a seperate body?[/color]

More efficient to write anyway, and perhaps to read, though maybe not if
there's too much of it. Also, a function whose body is in the class
definition is also inline, i.e., the same as putting the body outside, but
with the 'inline' specification.

DW

[Francis Glassborow]

Re: Could someone explain some code?

In article <I8H56z.9K@news .boeing.com>, Default User
<first.last@boe ing.com.invalid > writes[color=blue]
>Frank Looper wrote:
>[color=green][color=darkred]
>> > > #include <iostream>
>> > > using namespace std;
>> >
>> > This is a very bad idea. Try to avoid ever putting 'using'
>> > directives in a header.
>> >[/color]
>> Isn't that the standard? It's at least being taught as such...[/color]
>
>
>No, because then everyone who includes your header gets all of
>namespace std thrust into the global namespace, which might not be what
>they want.[/color]

But, unless I have completely lost track, we were not discussing a
header (I have never come across a header with main() in it.
[color=blue]
>
>Such using declarations should only be in implementation files. Header
>should just explicitly scope items from std.[/color]

Much better is to actually understand what using declarations and using
directives do.

--
Francis Glassborow ACCU
Author of 'You Can Do It!' see http://www.spellen.org/youcandoit
For project ideas and contributions: http://www.spellen.org/youcandoit/projects

[Victor Bazarov]

Re: Could someone explain some code?

Francis Glassborow wrote:[color=blue]
> In article <I8H56z.9K@news .boeing.com>, Default User
> <first.last@boe ing.com.invalid > writes
>[color=green]
>> Frank Looper wrote:
>>[color=darkred]
>>> > > #include <iostream>
>>> > > using namespace std;
>>> >
>>> > This is a very bad idea. Try to avoid ever putting 'using'
>>> > directives in a header.
>>> >
>>> Isn't that the standard? It's at least being taught as such...[/color]
>>
>>
>>
>> No, because then everyone who includes your header gets all of
>> namespace std thrust into the global namespace, which might not be what
>> they want.[/color]
>
>
> But, unless I have completely lost track, we were not discussing a
> header (I have never come across a header with main() in it.[/color]

You have completely lost track, then. See the post that started the
thread. The two lines quoted _were_ in a header. And I don't see any
'main' in it either.

V

[Default User]

Re: Could someone explain some code?

Francis Glassborow wrote:
[color=blue]
> In article <I8H56z.9K@news .boeing.com>, Default User
> <first.last@boe ing.com.invalid > writes[color=green]
> > Frank Looper wrote:
> >[color=darkred]
> >> > > #include <iostream>
> >> > > using namespace std;
> >> >
> >> > This is a very bad idea. Try to avoid ever putting 'using'
> >> > directives in a header.
> >> >
> >> Isn't that the standard? It's at least being taught as such...[/color]
> >
> >
> > No, because then everyone who includes your header gets all of
> > namespace std thrust into the global namespace, which might not be
> > what they want.[/color]
>
> But, unless I have completely lost track, we were not discussing a
> header (I have never come across a header with main() in it.[/color]

Nope. Here's the original code under discussion:

-----------

#ifndef _COUNTER_H
#define _COUNTER_H
#include <iostream>
using namespace std;

class Counter
{
public:
int count;
public:
* Counter(){count = 0;}
void operator ++() { ++count; }
int GetCount() { return count; }
void SetCount( int c ) { count = c; }
void PrintCount() { cout << "\n The count is " << count; }

};

class NewCounter:publ ic Counter
{
public:
* void operator --() { --count; }
};

#endif

[color=blue][color=green]
> >
> > Such using declarations should only be in implementation files.
> > Header should just explicitly scope items from std.[/color]
>
> Much better is to actually understand what using declarations and
> using directives do.[/color]

Indeed. Feel up to posting a tutorial? I didn't. The people in question
should find a good book that explains the subject. Now, if we only knew
of some web site or something that reviewed books ;)




Brian

[jeffc]

Re: Could someone explain some code?


"Victor Bazarov" <v.Abazarov@com Acast.net> wrote in message
news:Gi_td.1205 0$Ae.8510@newsr ead1.dllstx09.u s.to.verio.net. ..[color=blue]
> Gactimus wrote:[color=green]
> > Can anyone explain what the lines with the '*' by them do?
> >
> > -----------
> >
> > #ifndef _COUNTER_H
> > #define _COUNTER_H[/color]
>
> Lose the leading underscore on that macro name.
>[color=green]
> > #include <iostream>
> > using namespace std;[/color]
>
> This is a very bad idea. Try to avoid ever putting 'using' directives
> in a header.
>[color=green]
> >
> > class Counter
> > {
> > public:
> > int count;
> > public:
> > * Counter(){count = 0;}[/color]
>
> This one declares and defines the default constructor for this class.[/color]

I thought the * was actually part of the code, and I could not figure out what
it was supposed to do :-)