dev-cpp-users — Dev-C++ users discussion list

Re: [Dev-C++] opengl - WM_PAINT

[Astar <As...@tu...>]

Hello Neszt,

In my opinion, it will be better to draw on idle (not WM_PAIMT, but
when there is no any messages to translate in main loop). and
synchronize all moving/animation/etc by multiplying step to reciprocal for
fps.
I do so, and i have smooth moving/rotation/etc...
if you want source - try to my e-mail...

NT> As I know, all the paint function should use after WM_PAINT. It is
NT> also true for opengl display? I need to call the display() function 50
NT> times in every secounds. At this point of time, I use it after WM_PAINT,
NT> and it seems like, the calls are happens as fast as it can. My solution to
NT> aviod these quick calls is when the display() called, in the display() I
NT> check the glut elapsed time, and if this is greather than 1/50 sec, I let
NT> the display run over.

NT> This is not good, as the results shows. The opengl moovings, rotatings,
NT> and any other moovement not nicely continuous.

NT> So, Is there any mode to set somehow the window, to call the WM_PAINT in
NT> every 1/50 sec?

P.S. sorry for my english :)...

-- 
Best regards,
 Astar                            mailto:As...@tu...

RE: [Dev-C++] Passig by Reference Question

[Ioannis V. <iv...@em...>]

> -----Original Message-----
> From: dev...@li...
> [mailto:dev...@li...] On Behalf
> Of Andrι Macαrio Barros
> Sent: Thursday, April 03, 2003 8:25 PM
> To: Dev-Cpp-Users
> Subject: [Dev-C++] Passig by Reference Question
>
>
> Dear Sirs (and Ladies, if you are here),
>
>    Please, consider the three simple codes as follows:
>
> ##############################
> Program 1:
> 1 -#include <stdio.h>
> 2 -#include <stdlib.h>
> 3 -
> 4 -int sum(int, int);
> 5 -
> 6 -int main()
> 7 -{
> 8 -   int a, b, c;
> 9 -
> 10-   printf("Two Numbers Sum\n");
> 11-   printf("Enter First Number-->");
> 12-   scanf("%d", &a);
> 13-   printf("Enter Second Number-->");
> 14-   scanf("%d", &b);
> 15-   c = sum(a,b);
> 16-   printf("Sum of %d with %d is %d\n", a, b, c);
> 17-   system("PAUSE");
> 18-   return 0;
> 19-}
> 20-
> 21-int sum(int op1, int op2)
> 22-{
> 23-   int res;
> 24-
> 25-   res = op1 + op2;
> 26-   return(res);


or  return op1+op2; directly (but in reality sum() is not needed anyway).


> 27-}
> ##############################
> Program 2:
> 1 -#include <stdio.h>
> 2 -#include <stdlib.h>
> 3 -
> 4 -void sum(int, int, int *);
> 5 -
> 6 -int main()
> 7 -{
> 8 -   int a, b, c;
> 9 -
> 10-   printf("Two Numbers Sum\n");
> 11-   printf("Enter First Number-->");
> 12-   scanf("%d", &a);
> 13-   printf("Enter Second Number-->");
> 14-   scanf("%d", &b);
> 15-   sum(a, b, &c);
> 16-   printf("The Sum of %d with %d is %d\n", a, b, c);
> 17-   system("PAUSE");
> 18-   return 0;
> 19-}
> 20-
> 21-void sum(int op1, int op2, int *res)
> 22-{
> 23-   *res = op1 + op2;
> 24-
> 25-   return;


return statement is not needed here.



> 26-}
> ##############################
> Program 3:
> 1 -#include <stdio.h>
> 2 -#include <stdlib.h>
> 3 -
> 4 -void sum(int, int, int *);
> 5 -
> 6 -int main()
> 7 -{
> 8 -   int a, b, *c;
> 9 -
> 10-   c=(int *) malloc(sizeof(int));


Casting after malloc(), calloc() and realloc() IS NOT needed in C. K&R2 uses
casting because they tried the code in that time Storustrup's C++ compiler.
K&R2 also doesn't place a return statement before the end of main() which
was not proper C90. I assume that at least the first was fixed in later
editions.


So the above should be:

c=malloc(sizeof(int));

or (better):

c=malloc(sizeof(*c));





> 11-   printf("Two Numbers Sum\n");
> 12-   printf("Enter First Number-->");
> 13-   scanf("%d", &a);
> 14-   printf("Enter Second Number-->");
> 15-   scanf("%d", &b);
> 16-   sum(a, b, c);
> 17-   printf("The Sum of %d with %d is %d\n", a, b, *c);
> 18-   system("PAUSE");
> 19-   return 0;
> 20-}
> 21-
> 22-void sum(int op1, int op2, int *res)
> 23-{
> 24-   *res = op1 + op2;
> 25-   return;


return; not needed.



> 26-}
> ################
> Fight Between Programmers Scenario:
> A-I prefer to use program 2 instead of program 3 to
> demonstrate the way how
> to use passing
>   by reference over the original passing by value program 1.
> I prefer it
> because I find this
>   kind of manipulation in the books and itsn´t necessary to change the
> nature of the variables
>   (c integer variable in this case- look for line 8 in P2 and
> line 8 in P3);
> B-If we are already inside a function, and this function
> needs to pass a
> pointer variable to
>   other funcion, ok, is only use a passing way like line 16
> of Program 3
> (integer pointer c
>   variable in this case).
> ################
> My Question:
> Q1-Are both Programs, 2 and 3, correct? Please comment.
> Q2-Any opposition about my opinion in "A" Scenario?
> Q3-Any opposition about my opinion in "B" Scenario?
> Q4-Any additional comments?


See my comments above.




Ioannis Vranos

* Programming pages: http://www.noicys.freeurl.com
* Alternative URL: http://run.to/noicys


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Iraq Peace Pledge: http://www.peacepledge.org

[Dev-C++] Passig by Reference Question

[<and...@su...>]

Dear Sirs (and Ladies, if you are here),

   Please, consider the three simple codes as follows:

##############################
Program 1:
1 -#include <stdio.h>
2 -#include <stdlib.h>
3 -
4 -int sum(int, int);
5 -
6 -int main()
7 -{
8 -   int a, b, c;
9 -
10-   printf("Two Numbers Sum\n");
11-   printf("Enter First Number-->");
12-   scanf("%d", &a);
13-   printf("Enter Second Number-->");
14-   scanf("%d", &b);
15-   c = sum(a,b);
16-   printf("Sum of %d with %d is %d\n", a, b, c);
17-   system("PAUSE");
18-   return 0;
19-}
20-
21-int sum(int op1, int op2)
22-{
23-   int res;
24-
25-   res = op1 + op2;
26-   return(res);
27-}
##############################
Program 2:
1 -#include <stdio.h>
2 -#include <stdlib.h>
3 -
4 -void sum(int, int, int *);
5 -
6 -int main()
7 -{
8 -   int a, b, c;
9 -
10-   printf("Two Numbers Sum\n");
11-   printf("Enter First Number-->");
12-   scanf("%d", &a);
13-   printf("Enter Second Number-->");
14-   scanf("%d", &b);
15-   sum(a, b, &c);
16-   printf("The Sum of %d with %d is %d\n", a, b, c);
17-   system("PAUSE");
18-   return 0;
19-}
20-
21-void sum(int op1, int op2, int *res)
22-{
23-   *res = op1 + op2;
24-
25-   return;
26-}
##############################
Program 3:
1 -#include <stdio.h>
2 -#include <stdlib.h>
3 -
4 -void sum(int, int, int *);
5 -
6 -int main()
7 -{
8 -   int a, b, *c;
9 -
10-   c=(int *) malloc(sizeof(int));
11-   printf("Two Numbers Sum\n");
12-   printf("Enter First Number-->");
13-   scanf("%d", &a);
14-   printf("Enter Second Number-->");
15-   scanf("%d", &b);
16-   sum(a, b, c);
17-   printf("The Sum of %d with %d is %d\n", a, b, *c);
18-   system("PAUSE");
19-   return 0;
20-}
21-
22-void sum(int op1, int op2, int *res)
23-{
24-   *res = op1 + op2;
25-   return;
26-}
################
Fight Between Programmers Scenario:
A-I prefer to use program 2 instead of program 3 to demonstrate the way how
to use passing
  by reference over the original passing by value program 1. I prefer it
because I find this
  kind of manipulation in the books and itsn´t necessary to change the
nature of the variables
  (c integer variable in this case- look for line 8 in P2 and line 8 in P3);
B-If we are already inside a function, and this function needs to pass a
pointer variable to
  other funcion, ok, is only use a passing way like line 16 of Program 3
(integer pointer c
  variable in this case).
################
My Question:
Q1-Are both Programs, 2 and 3, correct? Please comment.
Q2-Any opposition about my opinion in "A" Scenario?
Q3-Any opposition about my opinion in "B" Scenario?
Q4-Any additional comments?

Regards
Andre

RE: [Dev-C++] why do we have to rename free() ?

[Ioannis V. <iv...@em...>]

> -----Original Message-----
> From: Ioannis Vranos [mailto:iv...@em...] 
> Sent: Thursday, April 03, 2003 7:32 PM
> To: 'Dev...@li...'
> Subject: RE: [Dev-C++] why do we have to rename free() ?
> 
> 
> > -----Original Message-----
> > From: dev...@li... 
> > [mailto:dev...@li...] On Behalf 
> > Of Khalid El-Kary
> > Sent: Thursday, April 03, 2003 6:53 PM
> > To: Dev...@li...
> > Subject: RE: [Dev-C++] why do we have to rename free() ?
> > 
> > 
> > so why does PHP source code compile similary on both windows 
> > and linux 
> > fellow ? :D
> 
> 
> 
> Because it is very new and the development happens from a 
> central team. Once it became mainstream and hundrends of 
> companies provided their own implementations with extensions 
> uncompatible among them, the need for an official standard will occur.



And if the creator wishes to leave his copyright so as other companies to
implement their own PHP implementations and a standard to emerge. GNU
licenses provide copyright protection. Noone can "steal" the product....






Ioannis Vranos
 
* Programming pages: http://www.noicys.freeurl.com
* Alternative URL: http://run.to/noicys


Anti-racism movement: http://www.positive-youthfoundation.org
Iraq Peace Pledge: http://www.peacepledge.org

RE: [Dev-C++] why do we have to rename free() ?

[Ioannis V. <iv...@em...>]

> -----Original Message-----
> From: dev...@li...=20
> [mailto:dev...@li...] On Behalf=20
> Of Khalid El-Kary
> Sent: Thursday, April 03, 2003 6:53 PM
> To: Dev...@li...
> Subject: RE: [Dev-C++] why do we have to rename free() ?
>=20
>=20
> so why does PHP source code compile similary on both windows=20
> and linux=20
> fellow ? :D



Because it is very new and the development happens from a central team. =
Once
it became mainstream and hundrends of companies provided their own
implementations with extensions uncompatible among them, the need for an
official standard will occur.





Ioannis Vranos
=20
* Programming pages: http://www.noicys.freeurl.com
* Alternative URL: http://run.to/noicys


Anti-racism movement: http://www.positive-youthfoundation.org
Iraq Peace Pledge: http://www.peacepledge.org

RE: [Dev-C++] why do we have to rename free() ?

[Khalid El-K. <kha...@ho...>]

> > -----Original Message-----
> > From: dev...@li...
> > [mailto:dev...@li...] On Behalf
> > Of Khalid El-Kary
> > Sent: Thursday, April 03, 2003 4:13 PM
> > To: Dev...@li...
> > Subject: RE: [Dev-C++] why do we have to rename free() ?
> >
> >
> > I thought GNU, Apache, PHP, OPENSSL try to make there code as
> > portable as
> > possible ?
>
>
>
>Portable is only the standard language.  If there is a standard named
>OPENSSL, it means that code for it would be portable to every system
>implementing it. Do not confuse Open Source with standards. Standards come
>from standards committees. But the Open Source movement usually uses the
>standards. :)

so why does PHP source code compile similary on both windows and linux 
fellow ? :D

>
>
>
>
>
>
>Ioannis Vranos
>
>* Programming pages: http://www.noicys.freeurl.com
>* Alternative URL: http://run.to/noicys
>
>
>Anti-racism movement: http://www.positive-youthfoundation.org
>Iraq Peace Pledge: http://www.peacepledge.org
>
>
>
>
>-------------------------------------------------------
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RE: [Dev-C++] browsing the source of Standard C++ Libs

[Ioannis V. <iv...@em...>]

> -----Original Message-----
> From: dev...@li...=20
> [mailto:dev...@li...] On Behalf=20
> Of Senthil Rajasekharan
> Sent: Thursday, April 03, 2003 6:09 PM
> To: dev...@li...
> Subject: [Dev-C++] browsing the source of Standard C++ Libs
>=20
>=20
> Hi,
>=20
> Does anyone know of a way to browse classes of
> Standard C++ Library implementation (either online or
> with a compiler distrib such as g++ ) ?
>=20
> -Senthil



Do you mean an online reference? A fast way to find what you want:


http://www.google.com.gr/search?q=3D%22C%2B%2B+standard+library%22+refere=
nce&i
e=3DUTF-8&oe=3DUTF-8&hl=3Del&lr=3D





Ioannis Vranos
=20
* Programming pages: http://www.noicys.freeurl.com
* Alternative URL: http://run.to/noicys


Anti-racism movement: http://www.positive-youthfoundation.org
Iraq Peace Pledge: http://www.peacepledge.org

[Dev-C++] browsing the source of Standard C++ Libs

[Senthil R. <sen...@ya...>]

Hi,

Does anyone know of a way to browse classes of
Standard C++ Library implementation (either online or
with a compiler distrib such as g++ ) ?

-Senthil


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RE: [Dev-C++] why do we have to rename free() ?

[Ioannis V. <iv...@em...>]

> -----Original Message-----
> From: dev...@li... 
> [mailto:dev...@li...] On Behalf 
> Of Khalid El-Kary
> Sent: Thursday, April 03, 2003 4:13 PM
> To: Dev...@li...
> Subject: RE: [Dev-C++] why do we have to rename free() ?
> 
> 
> I thought GNU, Apache, PHP, OPENSSL try to make there code as 
> portable as 
> possible ?



Portable is only the standard language.  If there is a standard named
OPENSSL, it means that code for it would be portable to every system
implementing it. Do not confuse Open Source with standards. Standards come
from standards committees. But the Open Source movement usually uses the
standards. :)






Ioannis Vranos
 
* Programming pages: http://www.noicys.freeurl.com
* Alternative URL: http://run.to/noicys


Anti-racism movement: http://www.positive-youthfoundation.org
Iraq Peace Pledge: http://www.peacepledge.org

RE: [Dev-C++] Passing programs from Borland 3.1 to Dev-C++ Pasar programas Borland 3.1 con Dev-C++

[Ioannis V. <iv...@em...>]

> -----Original Message-----
> From: dev...@li...=20
> [mailto:dev...@li...] On Behalf=20
> Of Carlos Garc=EDa del Monte
> Sent: Thursday, April 03, 2003 2:06 PM
> To: dev-cpp-users-list
> Subject: Re: [Dev-C++] Passing programs from Borland 3.1 to=20
> Dev-C++ Pasar programas Borland 3.1 con Dev-C++
>=20
>=20
> Can someone explain me how can I pass programs wirtten with=20
> Borland to=20
> Dev-C++, specially the graphic programs?
>=20


If the library is the same, and you do not use VCL but Win32 API, easily =
I
can guess.





Regards,

Ioannis Vranos
=20
* Programming pages: http://www.noicys.freeurl.com
* Alternative URL: http://run.to/noicys


Anti-racism movement: http://www.positive-youthfoundation.org
Iraq Peace Pledge: http://www.peacepledge.org

RE: [Dev-C++] why do we have to rename free() ?

[Khalid El-K. <kha...@ho...>]

> > -----Original Message-----
> > From: dev...@li...
> > [mailto:dev...@li...] On Behalf
> > Of Khalid El-Kary
> > Sent: Thursday, April 03, 2003 5:57 AM
> > To: Dev...@li...
> > Subject: [Dev-C++] why do we have to rename free() ?
> >
> >
> > hi fellows,
> >
> > when i checked a lot of big project's source codes, I have found them
> > replacing basic funtion names with new function names, and
> > sometimes with a
> > new way of functioning for example:
> >
> > free() -> OPENSSL_free()
> > malloc() -> gnew(type, number of blocks)
> >
> > how can this be useful ?, does it have a thing to do with
> > portability ?, and
> > if not what's the difference in functionality ?
>
>
>Additional, non-portable functionality.

I thought GNU, Apache, PHP, OPENSSL try to make there code as portable as 
possible ?

>
>
>
>Ioannis Vranos
>
>* Programming pages: http://www.noicys.freeurl.com
>* Alternative URL: http://run.to/noicys


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Re: [Dev-C++] dynamic or stack allocation ...

[Khalid El-K. <kha...@ho...>]

thanx for the very detailed reply :-)

>Small OS preallocates the stack to a fixed size at startup. OS using
>virtual memory and MMU normally let's the stack grow at runtime. This
>stack growth is one level below the use of dynamic allocation on heap,
>since the OS uses the memory paging scheme of the processor.
>
>One method the OS may use is to add a write-protected guard page last on
>the stack. As soon as the program tries to write to this guard page, the
>OS gets a memory protection error. It detects that the stack is about to
>overflow and oens the guard page for writing and adds a new guard page 4kB
>(for x86) higher on the stack. This scheme may fail for a method using a
>large auto buffer, since if the buffer is larger than the guard page, the
>first write might come at a an address AFTER the guard page. A lot of
>compilers will add extra code for functions with large auto variables,
>where the extra funcrion prolog touches the stack in 4kB steps to let the
>OS detect and add the needed number of new pages.
>
>One other method for the OS to handle the stack is to have a very large
>hole in the virtual address space after the end of the stack. If an access
>comes to the nearest MB (or whatever) of the stack top, the OS then
>assumes that it isn't a bad pointer access but a function with large auto
>variables, and then fills up the stack with needed number of new pages.
>
>A lot of OS does NOT allow the stack to grow for any threads that gets
>started by the main process. This is because the virtual address space of
>most processors is a bit cramped, and to leave large address map holes for
>the individual stacks to grow into would seriously reduce number of
>concurrent threads the process might have. At creation, the process have
>to specify the maximum stack size needed for the new threads and then the
>stacks are placed end-to-end in the virtual memory address map.
>
>Auto-allocated data is only possible when life span of a variable follows
>the call nesting of the used functions, since the variables will be
>automatically released when the function returns. No function might return
>a pointer to one of it's auto variables, and have the caller reference
>that pointer.
>
>
>While there exists schemes for allocation of variable-sized data on the
>stack, they are normally plagued by incompatiblities between compilers,
>used processors etc and should normally not be used, i.e. if you don't
>know the needed size in the beginning, the recommendation is to go for
>heap allocation.
>
>If the needed memory block is very large, heap memory should also be used,
>since the OS might have a stack size limit a lot smaller than malloc/new
>might support. Also, some combinations of compilers and OS fails to detect
>and auto-grow the stack for some scenarios with large auto variables.
>
>
>A single call for dynamic allocation is not a problem. It's when the
>allocation and/or release is in a loop or a time-critical part of a
>program you'll have to watch out for the speed issue.
>
>For embedded programming there's the extra problem that asynchronous
>events, such as interrupt service routines may normally not call most OS
>and library functions, since that might result in deadlock. If a thread is
>in a critical section the ISR needs access to, the OS can't just park the
>ISR until the thread releases the critical section.
>
>/Per W
>
>On Thu, 3 Apr 2003, Khalid El-Kary wrote:
>
> > Hi fellows,
> >
> > right now i know that memory in the stack gets allocated for once during 
>the
> > start-up of the programm, and dynamically allocated memory gets 
>allocated
> > while the programm is running.
> >
> > stack memory is faster at execution.
> > dynamic memory is slower (the time consumed by malloc/free)
> >
> > but ...
> >
> > I want to know when exactly should i use stack memory and when exactly
> > should i use dynamic memory ?
> >
> > thanx in advance
> >
> > Regards,
> > Khalid Al-Kary
> >
> >
> >
> >
> >
> > _________________________________________________________________
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Re: [Dev-C++] Passing programs from Borland 3.1 to Dev-C++ Pasar programas Borland 3.1 con Dev-C++

[<cg...@wo...>]

Can someone explain me how can I pass programs wirtten with Borland to=20
Dev-C++, specially the graphic programs?

Si utilizas el archivo de cabecera graphics.h, puedes bajarte el zip de=20
winbgim, que es una adaptaci=F3n para Dev. No tengo aqu=ED la direcci=F3n=
,=20
pero buscando en google la tendr=E1s en la primera p=E1gina de resultados=
=2E
(I talked a bit about winbgim and graphics.).
No puedo  contestarte completamente respeco qu=E9 pueda hacerse, puesto=20
que nunca he usado Borland.
(I say I've never used Borland, so I can't give a serious answer)

JOSE LUIS GARCIA GARCIA wrote:

> =BFSi alguien es tan amable de explicarme como puedo pasar programas=20
> escritos en Borland 3.1, especialmente gr=E1ficos, al entorno Dev-C++.
> Gracias.

Re: [Dev-C++] itoa - simple implementation

[Per W. <pw...@ia...>]

But the following code works:

char buf1[30],buf2[30],*p1 = itoa(9,buf1), *p2 = itoa(10,buf2);

It's quick since it doesn't use dynamic memory. It's reentrant since the
thread uses it's own buffers and not a global buffer hidden somewhere
within the itoa() implementation.

It supports multiple stored answers for each thread.

It may never leak memory, since the buffers are auto-allocated.

That's why just about all itoa() implementations available with compilers
or OS are taking the pointer as an input parameter.

/Per W

On Wed, 2 Apr 2003, Luigi Santillo wrote:

> On Wed, Apr 02, 2003 at 01:48:06PM +0300, Ioannis Vranos wrote:
> > This code is not good. Assume this:
> >
> >
> > char *p=itoa(9), *q=itoa(10);
> >
> >
> > I suggest to return a pointer on memory on the free store.
> >
>
> Hello,
>
> You are right, my simple implementation does not cope well
> with the above situation. I used the free store in my first
> implementation, then, following some advice, I attempted to
> use a static array, as that would probably be faster.
>
> Thanks for your suggestion
> --
> >> gisan >>
>
>
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Re: [Dev-C++] about "reentering code" [was: itoa - simple implementation]

[Per W. <pw...@ia...>]

Since the caller supplies the buffer, itoa() then doesn't need to touch
any global variables.

That makes it possible for one thread to call itoa(), a task switch to
happen and a new new thread to call itoa() without either a static buffer
being corrupted by the two concurrent calls, or the second thread being
blocked by a critical section.

With a unprotected static buffer owned by itoa(), a second call from
another thread while itoa() runs, or before the first thread is done with
the returned pointer, would clear the static buffer and immediately try to
reuse it.

If the static buffer is protected by a critical section or mutex, then
only one thread at a time may use the buffer INSIDE itoa(), while any
other callers will be blocked until the first itoa() call returns.
However, the calling program will not be able to use the static buffer
before the next call from the other thread destroys the buffer.

If the buffer is dynamically allocated, each concurrent call of itoa()
will have their own buffer. This makes the call thread-safe. However, the
allocation malloc(), calloc(), strdup(), new or whatever, must access a
global list of available memory blocks for performing the allocation. To
make these functions thread-safe, they will have to protect the actual
allocation within a mutex or critical section. While this makes them
thread-safe, it doesn't make them fully reentrant, since a second
allocation call may not finish until the first allocation is through. This
will force the second thread - doesn=B4t matter how high prio it has - to
lock up until the first allocation is done.

If implementing a ISR - interrupt service routine - it would not be
alloced to cal the allocation function, so it woun't be allowed to call an
itoa() that uses dynamic memory. That is because while the interrupt
routine is active, there isn't possible for the OS to activate any
threads. The thread calling itoa() would then permanently lock the ISR
from ending, resulting in a dead-lock.

When you send in the buffer as a parameter to itoa(), you never get that
kind of problem, since each caller themself arrange for needed memory in a
suitable way. All running tasks have their own stack so an auto-allocated
buffer works find. As long as the buffer isn't large enough, the ISR may
also allocate a buffer on the stack - it will denepnding on OS either have
it's own OS-reserved stack, or using the free area of the currently
running thread's stack.

/Per W

On Wed, 2 Apr 2003, Luigi Santillo wrote:

> Hello Per,
>
> I see that you have mentioned that an implementation of itoa
> which has the interface:
>
> void itoa(int n, char *s);
>
> would be "reentrant". This concept is not clear to me, I would
> appreciate if you could elaborate a little about it, for instance
> you could point out the weakness (or "reentrancy" problems) related
> to the interface
>
> char *itoa(int n);
>
> and how these would be solved adopting the 2 parameters - void returning =
-
> function.
>
> TIA
> --
> >> gisan >>
>
>
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[Dev-C++] CALCULATOR

[Dondolo M. <MDo...@OL...>]

Hi all.

I am getting there with c++. there is one question I would like to ask. I
was experimenting with a simple calculator program that I wrote. What the
program does is it prompts you to enter the first number, then the second
number. The next step , you are prompted to choose what you wanna do with
the numbers eg Multiply, add...

What I want is when the user selects his choice, the answer must be
displayed on a clean "page" and not show all the other previous info ...ie,
the numbers being calculated or the menu to select from.

//-----------

#include<iostream.h>
#include<stdlib.h>

//A funcion that adds two numbers
float Add(float x, float y)
{
return (x+y);
}
//-----------------------------
float Multiply(float x, float y)
{
return (x*y);
}
//----------------------------
float Minus(float x, float y)
{
return (x-y);
}
//--------------------
float Divide( float x, float y)
{
return (x/y);
}

//---------
//--------

main()// main function
{
float a,b,c;
int Ans;
cout<<"Enter first number : "; 
cin>>a;
cout<<"...and the second number : ";
cin>>b;
cout<<"\n";
cout<< "\t\t\t 1)ADD\n"
       "\t\t\t 2)DIVIDE\n"
       "\t\t\t 3)MULTIPLY\n"
       "\t\t\t 4)SUBTRACT\n";   
cout<<"_";cin>>Ans;
if (Ans==1)
{
c=Add(a,b);
cout<<c;
}  
     if (Ans==2)
        {
        c= Divide(a,b);
        cout<<c;
         }
               if(Ans==3)
                   {
                     c=Multiply(a,b);
                     cout<<c;
                      }
                 
                           if(Ans==4)
                                {
                                  c= Minus(a,b);
                                  cout<<c;
                                   }
 

      
           

system("PAUSE");
}  



Mpho Dondolo
Support Analyst
Computer Sciences Corp. (CSC) 
Tel: +27 21 503 0059
Fax: +27 21 509 5619
Cell: +27 84 337 1468
mdo...@cs...
mdo...@ol...

[Dev-C++] opengl - WM_PAINT

[Neszt T. <ne...@ss...>]

Hello!

As I know, all the paint function should use after WM_PAINT. It is
also true for opengl display? I need to call the display() function 50
times in every secounds. At this point of time, I use it after WM_PAINT,
and it seems like, the calls are happens as fast as it can. My solution to
aviod these quick calls is when the display() called, in the display() I
check the glut elapsed time, and if this is greather than 1/50 sec, I let
the display run over.

This is not good, as the results shows. The opengl moovings, rotatings,
and any other moovement not nicely continuous.

So, Is there any mode to set somehow the window, to call the WM_PAINT in
every 1/50 sec?


Thank Your help in advance,

Regards,
 Neszt Tibor

Re: [Dev-C++] itoa - atoi : another implementation

[Ricardo R. <ri...@po...>]

you are right, you dont need to call strlen( )
and by the way, to include the header "string.h".

Ricardo.

Antw: [Dev-C++] Newbie

[Frank W. <F.W...@wi...>]

Hi Kris,

I also work with the Cygwin system, so you must modify the directories
in the compiler environment settings form the default (for MinGW) to the
corresponding for Cygwin .

Hope that helps

Greetings

Frank

>>> Kris Nackaerts <kna...@gm...> 04/03 9:46  >>>
Dear,

I downloaded and installed dev-C++ version 4.9.8.0 but cannot compile 
anything. I get the following message:

cannot find entry symbol_mainCRTstartup; defaulting to 00401000
linker error: undefined reference to 'strcpy'
etc.

I can compile files with g++ version 2.95.3-5 in Cygwin which I used 
uptill now. The progra contains nothing special, reading ascii data, 
some basic calculations, export again+.

Any help would be greatly appreciated.

Kris



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[Dev-C++] Newbie

[Kris N. <kna...@gm...>]

Dear,

I downloaded and installed dev-C++ version 4.9.8.0 but cannot compile 
anything. I get the following message:

cannot find entry symbol_mainCRTstartup; defaulting to 00401000
linker error: undefined reference to 'strcpy'
etc.

I can compile files with g++ version 2.95.3-5 in Cygwin which I used 
uptill now. The progra contains nothing special, reading ascii data, 
some basic calculations, export again+.

Any help would be greatly appreciated.

Kris

[Dev-C++] about "reentering code" [was: itoa - simple implementation]

[Luigi S. <gi...@li...>]

Hello Per,

I see that you have mentioned that an implementation of itoa
which has the interface:

void itoa(int n, char *s);

would be "reentrant". This concept is not clear to me, I would
appreciate if you could elaborate a little about it, for instance
you could point out the weakness (or "reentrancy" problems) related
to the interface

char *itoa(int n);

and how these would be solved adopting the 2 parameters - void returning - 
function. 

TIA
-- 
>> gisan >>

Re: [Dev-C++] itoa - simple implementation

[Luigi S. <gi...@li...>]

On Wed, Apr 02, 2003 at 01:48:06PM +0300, Ioannis Vranos wrote:
> This code is not good. Assume this:
> 
> 
> char *p=itoa(9), *q=itoa(10);
> 
> 
> I suggest to return a pointer on memory on the free store.
> 

Hello,

You are right, my simple implementation does not cope well
with the above situation. I used the free store in my first
implementation, then, following some advice, I attempted to 
use a static array, as that would probably be faster. 

Thanks for your suggestion
-- 
>> gisan >>

Re: [Dev-C++] dynamic or stack allocation ...

[Per W. <pw...@ia...>]

Small OS preallocates the stack to a fixed size at startup. OS using
virtual memory and MMU normally let's the stack grow at runtime. This
stack growth is one level below the use of dynamic allocation on heap,
since the OS uses the memory paging scheme of the processor.

One method the OS may use is to add a write-protected guard page last on
the stack. As soon as the program tries to write to this guard page, the
OS gets a memory protection error. It detects that the stack is about to
overflow and oens the guard page for writing and adds a new guard page 4kB
(for x86) higher on the stack. This scheme may fail for a method using a
large auto buffer, since if the buffer is larger than the guard page, the
first write might come at a an address AFTER the guard page. A lot of
compilers will add extra code for functions with large auto variables,
where the extra funcrion prolog touches the stack in 4kB steps to let the
OS detect and add the needed number of new pages.

One other method for the OS to handle the stack is to have a very large
hole in the virtual address space after the end of the stack. If an access
comes to the nearest MB (or whatever) of the stack top, the OS then
assumes that it isn't a bad pointer access but a function with large auto
variables, and then fills up the stack with needed number of new pages.

A lot of OS does NOT allow the stack to grow for any threads that gets
started by the main process. This is because the virtual address space of
most processors is a bit cramped, and to leave large address map holes for
the individual stacks to grow into would seriously reduce number of
concurrent threads the process might have. At creation, the process have
to specify the maximum stack size needed for the new threads and then the
stacks are placed end-to-end in the virtual memory address map.

Auto-allocated data is only possible when life span of a variable follows
the call nesting of the used functions, since the variables will be
automatically released when the function returns. No function might return
a pointer to one of it's auto variables, and have the caller reference
that pointer.


While there exists schemes for allocation of variable-sized data on the
stack, they are normally plagued by incompatiblities between compilers,
used processors etc and should normally not be used, i.e. if you don't
know the needed size in the beginning, the recommendation is to go for
heap allocation.

If the needed memory block is very large, heap memory should also be used,
since the OS might have a stack size limit a lot smaller than malloc/new
might support. Also, some combinations of compilers and OS fails to detect
and auto-grow the stack for some scenarios with large auto variables.


A single call for dynamic allocation is not a problem. It's when the
allocation and/or release is in a loop or a time-critical part of a
program you'll have to watch out for the speed issue.

For embedded programming there's the extra problem that asynchronous
events, such as interrupt service routines may normally not call most OS
and library functions, since that might result in deadlock. If a thread is
in a critical section the ISR needs access to, the OS can't just park the
ISR until the thread releases the critical section.

/Per W

On Thu, 3 Apr 2003, Khalid El-Kary wrote:

> Hi fellows,
>
> right now i know that memory in the stack gets allocated for once during the
> start-up of the programm, and dynamically allocated memory gets allocated
> while the programm is running.
>
> stack memory is faster at execution.
> dynamic memory is slower (the time consumed by malloc/free)
>
> but ...
>
> I want to know when exactly should i use stack memory and when exactly
> should i use dynamic memory ?
>
> thanx in advance
>
> Regards,
> Khalid Al-Kary
>
>
>
>
>
> _________________________________________________________________
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RE: [Dev-C++] why do we have to rename free() ?

[Ioannis V. <iv...@em...>]

> -----Original Message-----
> From: dev...@li... 
> [mailto:dev...@li...] On Behalf 
> Of Khalid El-Kary
> Sent: Thursday, April 03, 2003 5:57 AM
> To: Dev...@li...
> Subject: [Dev-C++] why do we have to rename free() ?
> 
> 
> hi fellows,
> 
> when i checked a lot of big project's source codes, I have found them 
> replacing basic funtion names with new function names, and 
> sometimes with a 
> new way of functioning for example:
> 
> free() -> OPENSSL_free()
> malloc() -> gnew(type, number of blocks)
> 
> how can this be useful ?, does it have a thing to do with 
> portability ?, and 
> if not what's the difference in functionality ?


Additional, non-portable functionality.



Ioannis Vranos
 
* Programming pages: http://www.noicys.freeurl.com
* Alternative URL: http://run.to/noicys

RE: [Dev-C++] dynamic or stack allocation ...

[Ioannis V. <iv...@em...>]

> -----Original Message-----
> From: dev...@li... 
> [mailto:dev...@li...] On Behalf 
> Of Khalid El-Kary
> Sent: Thursday, April 03, 2003 4:05 AM
> To: Dev...@li...
> Subject: [Dev-C++] dynamic or stack allocation ...
> 
> 
> Hi fellows,
> 
> right now i know that memory in the stack gets allocated for 
> once during the 
> start-up of the programm,


Not only.


> and dynamically allocated memory 
> gets allocated 
> while the programm is running.
> 
> stack memory is faster at execution.


In creation/destruction.


> dynamic memory is slower (the time consumed by malloc/free)


The time cost is not to be taken under consideration in nowadays ordinary
systems (that is everything else than a microcontroller).


> 
> but ...
> 
> I want to know when exactly should i use stack memory and 
> when exactly 
> should i use dynamic memory ?


Stack memory is very limited (typicaly 64 kb total available for a DOS
program). The rest of memory can be seen as free store.



Ioannis Vranos
 
* Programming pages: http://www.noicys.freeurl.com
* Alternative URL: http://run.to/noicys