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FIDO MESSAGE AREA==> TOPIC: 203 C++           Ref: ECL00009 Date: 08/16/97
From: MATHIEU BOUCHARD                                      Time: 02:46am
\/To: PETER HAYWOOD                                       (Read 3 times)
Subj: Re: Signs of numbers

 PH> int s, i;
 PH> i = -647;       /* set i to some value */
 PH> s = (i < 0 ? -1 : 1);           /* set s to -1 if i<0 or 1 if i>=0 */
 PH>   You could even define a simple macro to perform the same task as
 PH> your VB function:
by the way this SGN is afaik standard in all versions of BASIC or at
least TRS-80 Color Basic, GWBASIC, QuickBASIC, PowerBASIC, and most
others.
 PH> #define Sgn(x) (x < 0 ? -1 : x > 0 ? 1 : 0)
i would recommend a non-macro one, that avoids nasty side effects,
enforces type-checking, and clears out most nameconflicts:
template <class Any> inline int sgn (Any x) { return x<0 ? -1 : x>0; }
matju
--- Terminate 4.00/Pro
 * Origin: The Lost Remains Of SatelliteSoft BBS (1:163/215.42)
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FIDO MESSAGE AREA==> TOPIC: 203 C++           Ref: ECL00010 Date: 08/16/97
From: MATHIEU BOUCHARD                                      Time: 02:58am
\/To: BENJAMIN L MCGEE                                    (Read 3 times)
Subj: replies here ->[]

 BLM> How would you define "ascribing to much responsibility to the 
 BLM> constructor?"  Is this to much... 
 BLM> manifest::manifest(){ 
 BLM>      filename = new char[FILENAME_MAX]; 
 BLM>      while (!select(filename, FILENAME_MAX - 1)); 
 BLM>      mstreamp = new ifstream(filename); 
 BLM> } 
this is okay. i often write bigger constructors. (i know the language
well enough to know when copies of objects are created, and i make sure
references are used everywhere, and make sure no temporaries are
created.)
matju
--- Terminate 4.00/Pro
 * Origin: The Lost Remains Of SatelliteSoft BBS (1:163/215.42)
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FIDO MESSAGE AREA==> TOPIC: 203 C++           Ref: ECM00000 Date: 08/17/97
From: TEEMU FRISK                                           Time: 07:16pm
\/To: ALL                                                 (Read 3 times)
Subj: cannot make 3d

Hi everybody!
I tried to make little 3d-program with one wireframe cube. I got all the 
points drawed but result wasn't 3d, far of it. So how can I make simple 
little 3d-engine and draw/move lines/pixels with it?
Is there any 3d-related programming site on the net where I can get more 
fo?
--- BBBS/2 v3.42 ToMmIk-6v
 * Origin: BCG-Box 4 (2:222/0)
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FIDO MESSAGE AREA==> TOPIC: 203 C++           Ref: ECM00001 Date: 08/18/97
From: KURT KUZBA                                            Time: 06:51am
\/To: JOSH JACKSON                                        (Read 3 times)
Subj: Mpython

JJ>   They are the knights that say neep! not nee.
#include <iostream.h>
#include <string.h>
#include <ctype.h>
class Knights_who_say_NEEK
{
public:
   Knights_who_say_NEEK(char*);
   ~Knights_who_say_NEEK(void);
   int pass_by(char*);
private:
   char *Neek;
};
void Knights_who_say_NEEK::Knights_who_say_NEEK(char *P = "shrubbery")
{
   if(*P)
   {
      Neek = new char[strlen(P) + 1];
      strcpy(Neek, P);
   }
}
void Knights_who_say_NEEK::~Knights_who_say_NEEK(void)
{
   delete []Neek;
}
int Knights_who_say_NEEK::pass_by(char *S)
{
   int pass = 0;
   if(!strcmp(S, Neek))
   {
      cout << "You may pass" << endl;
      pass = 1;
   }
   else
   {
      char *p = Neek;
      cout << "You may not pass until you bring us...\n"
            "...  A ";
      for(; *p; p++)
         cout << char(toupper(*p));
      cout << "!!" << endl;
   }
   return pass;
}
void nicky_nicky_nicky_nicky_nU(Knights_who_say_NEEK &K, char *P)
{
   K.pass_by("");
   cout << "( giving them a " << P << ". )" << endl;
   K.pass_by(P);
}
int main(void)
{
   char c;
   Knights_who_say_NEEK *knights =
      new   Knights_who_say_NEEK;
   Knights_who_say_NEEK *knights2 =
      new   Knights_who_say_NEEK ("cookie");
   cout << "\n\n\n\n You have encountered the dreaded"
         " Knights Who Say Neek!\n You must comply with"
         " their demands to continue!\n\n" << flush;
   nicky_nicky_nicky_nicky_nU(*knights, "shrubbery");
   delete knights;
   nicky_nicky_nicky_nicky_nU(*knights2, "cookie");
   delete knights2;
   cout << "Enter any character and ENTER to exit." << endl;
   cin >> c;
   return 0;
}
> ]<urt   (NFX)
> You're trying to make me paranoid, but I'm on to your tricks
---
 * Origin: *YOPS ]I[* 3.1 GIG * RA/FD/FE RADist * Milwaukee, WI (1:154/750)
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FIDO MESSAGE AREA==> TOPIC: 203 C++           Ref: ECN00000 Date: 08/15/97
From: BALOG PAL                                             Time: 03:09am
\/To: BENJAMIN L MCGEE                                    (Read 3 times)
Subj: couple of ?'s

                            Hi, Benjamin L Mcgee!
On 11 Aug 97  15:38:00 you wrote to All
 BLM> class manifest {
 BLM> public:
 BLM>  manifest();
 BLM>  manifest(const char *filename);
 BLM>  ~manifest();
 BLM>
 BLM>  void report_name();
report_name() const; ???
 BLM>
 BLM> private:
 BLM>  char* select(char *filename, int len);
probably ... const char *filename .. is better
 BLM>  char      *filename;
 BLM>  ifstream  *mstreamp;
 BLM> };
 BLM> manifest::manifest(const char* manfile){
 BLM> filename = new char[FILENAME_MAX];
 BLM> strncpy(filename, manfile, FILENAME_MAX - 1);
If the given filename is long enough I think you'll end up with a not 0-
terminated string.
 BLM> mstreamp = new ifstream(filename);
 BLM> }
 BLM> How do I handle errors in opening the ifstream?
Probably the same way you handle all other errors associated with the stream.
You probably must supply some interface to ask or clear its status.
 BLM> Is it a good idea perhaps, to just allocate space for filename within
 BLM> the constructor and then handle everything else in a manifest::init()
 BLM> member?  That would seem redundant to me but perhaps overloading
 BLM> constructors is already redundant.
Er, I think moving common code to a single function is not redundant but
removes ill redundancy.
Overloading ctors is not redundant either but in your case I'd better use a
single ctor of form:
 BLM>  manifest(const char *filename = 0);
That serves for both of your ctors after you insert an if branch.
Paul
... Veni, Vidi, VCR--I came, I saw, I taped
--- OS/2 Warp
 * Origin: The FlintStones' Cave in BedRock (2:371/20)
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FIDO MESSAGE AREA==> TOPIC: 203 C++           Ref: ECN00001 Date: 08/17/97
From: BALOG PAL                                             Time: 06:57am
\/To: JAVIER KOHEN                                        (Read 3 times)
Subj: C++ or ASM?

                              Hi, Javier Kohen!
On 11 Aug 97  21:55:40 you wrote to Cameron Clark
 JK> Actually I'm just casting from (void *) to (virtual char *), see how
 JK> confusing it is!?
What the heck is a (virtual char *) ?
 JK> const_cast<> can change const but volatile, too.
 JK> static_cast<> can change anything (mmm... not very sure about it :-),
No. You can't cast to a less cv qualified type. So you can't cast away
constness unintentionally using this. That is one of this operator's main
purpose.
Paul
... (C)ontrol (A)lt (B)ye
--- OS/2 Warp
 * Origin: The FlintStones' Cave in BedRock (2:371/20)
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FIDO MESSAGE AREA==> TOPIC: 203 C++           Ref: ECN00002 Date: 08/17/97
From: BALOG PAL                                             Time: 07:05am
\/To: BENJAMIN L MCGEE                                    (Read 3 times)
Subj: replies here ->[]

                            Hi, Benjamin L Mcgee!
On 13 Aug 97  23:14:00 you wrote to All
 BLM> How would you define "ascribing to much responsibility to the
 BLM> constructor?"  Is this to much...
 BLM>
 BLM> manifest::manifest(){
 BLM> filename = new char[FILENAME_MAX];
 BLM> while (!select(filename, FILENAME_MAX - 1));
 BLM> mstreamp = new ifstream(filename);
 BLM> }
Depends on what you want of it.
I see no good reason to create an ifstream on the fly. You can simply have a
member of type ifstream in your class, that will save a heap operation (and
another in dtor). filename is also questionable is you use a platform tith
nonlimited stack.
Is select is a user-interfaced function, it really can be misplaced in the
ctor. There can be situations where you want to instantiate the class but not
immediately use it. Then you better leave the filename not selectes right in
the ctor, but in a separate member function. But these all depensd on the
purpose of the class.
Paul
... Beware of programmers who carry screwdrivers
--- OS/2 Warp
 * Origin: The FlintStones' Cave in BedRock (2:371/20)
---------------

FIDO MESSAGE AREA==> TOPIC: 203 C++           Ref: ECN00003 Date: 08/17/97
From: BALOG PAL                                             Time: 07:16am
\/To: DANIEL JONES                                        (Read 3 times)
Subj: Sunir ventures into C++

                              Hi, Daniel Jones!
On 13 Aug 97  07:06:00 you wrote to Aare Tali
 AT>         for (i = 0; i < 5; i++)
 AT>             do_something(i);
 AT>         for (int j = 0; j < 5; j++)
 AT>             do_something_else(j);
 AT>         if (i < 5)
 AT>             not_everything_was_done_with_i();
 AT>         if (j < 5)
 DJ> Did you test this? If so, with what compiler?
Probably yes, and using an erlyer compiler
 DJ> With BC++ 5.01, I get an error:
 DJ> Undefined symbol 'j'
 DJ> Why?  Because the for() loop defines a block.  j is local to that
 DJ> block, and is out of scope in your "if(j < 5)" statement.  As I recall,
 DJ> this was a matter of some debate, and wasn't implemented in early
 DJ> versions of C++.  I'm reasonably certain that BC++ 3.1 allowed the
 DJ> above code.
Yes, the scoping rule of variables defined in for() changed in the latest C++
draft, so the above code will get an error in the compilers based on the
draft.
Previously C++ handled the for (int i= ...) like C: it broke the for
statement to
A;
while(b)
{
... the block
C;
}
This way wariables defined at the first part went to the csope of the outer
block. The change made them to belong in the scope of the block of for.
Paul
... WORN disk: Write Once Read Never disk
--- OS/2 Warp
 * Origin: The FlintStones' Cave in BedRock (2:371/20)
---------------

FIDO MESSAGE AREA==> TOPIC: 203 C++           Ref: ECN00004 Date: 08/17/97
From: BALOG PAL                                             Time: 07:25am
\/To: DANIEL JONES                                        (Read 3 times)
Subj: Sunir ventures into C++

                              Hi, Daniel Jones!
On 14 Aug 97  07:06:00 you wrote to Jerry Coffin
 DJ> cin << &Number;
 DJ> vice
 DJ> cin << Number;
cin >> Number !
Paul
... Happiness is a warm gun
--- OS/2 Warp
 * Origin: The FlintStones' Cave in BedRock (2:371/20)
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FIDO MESSAGE AREA==> TOPIC: 203 C++           Ref: ECN00005 Date: 08/18/97
From: DARIN MCBRIDE                                         Time: 07:16pm
\/To: JERRY COFFIN                                        (Read 3 times)
Subj: volatile objects?

Jerry, or anyone else for that matter,...
I'm trying, mostly for the sake of learning, to write a simple multi-threaded
comm class.  Most of it seems to work, so far, except the queues.  I'd like
to have a write queue and read queue.  That seems simple - there's a deque in
the STL.  Except that it doesn't really want to work if I make it volatile. 
If it is volatile, the compiler complains.  If it isn't volatile, it becomes
really funny - I write to the serial port fine, but reading doesn't always
seem to work... if I don't give it a long enough delay, the "AT" coming back
from the modem (which I see in a line monitor) only is discovered if I give
it a long enough timeout.  I'm sure volatile would help here - if I could
figure out what I was doing with it.  :-)
Leaving it non-volatile and then removing the thread/queue for reading may
work.  However, I'm suspicious that the write queue may not work in stress
situations (i.e., trying to send a file).
Any ideas?
... Press <Ctrl-Alt-Del> now to access the pirate software.
--- FastEcho 1.46
 * Origin: House of Fire BBS - Toronto - (416)601-0085 - v.34 (1:250/536)