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Holding pointers to functions as values in a std::map

Alexandru Savescu24-May-02 2:43

24-May-02 2:43

Hello,

I have defined a pointer to a function that returns int and receives 3 doubles like this:
<pre>
typedef int ( *fptr)(double tp, double etc, double atd);
</pre>

And I have declared one function of the type above named f1.

I want to hold a map of CString and pointers to functions so I declared like this:

map <CString, fptr> MyMap;

MyMap.insert (pair <CString, fptr> ("aaa", f1); // error here
and the error is
pair<class CString,int (__cdecl*)(double,double,double)>::pair<class CString,int (__cdecl*)(double,double,double)>' : none of the 2 overloads can convert parameter 2 from type 'int (doub
le,double,double)'

Best regards,
Alexandru Savescu

Re: Holding pointers to functions as values in a std::map

C^hris L^osinger24-May-02 3:03

C^hris L^osinger

24-May-02 3:03

try : MyMap.insert (pair ("aaa", &f1));

-c

Cheap oil. It's worth it!

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Re: Holding pointers to functions as values in a std::map

Alexandru Savescu24-May-02 3:13

Alexandru Savescu

24-May-02 3:13

Thanks it worked.

It was obvious! Wink | ;)

Best regards,
Alexandru Savescu

I'm doing similar but why won't work

24-May-02 3:45

Hi,

I'm doing something similar, but i don't have luck Frown | :(

<br />
typedef bool (*func)(CClient *, CPacketBase *);<br />
typedef std::map<long, func> CHandlerMap;<br />

and I declared a function called

<br />
bool CPacketHandler::prcLogin(CClient *pclt, CPacketBase *pak)<br />
{<br />
 ....<br />
  return true;<br />
}<br />

I tried to insert the function into the map like:

<br />
m_HandlerMap.insert(CHandlerMap::value_type(1001, &prcLogin));<br />

The error I got is :

error C2276: '&' : illegal operation on bound member function expression
Error executing cl.exe.

Re: I'm doing similar but why won't work

Joaquín M López Muñoz24-May-02 3:54

Joaquín M López Muñoz

24-May-02 3:54

The member function has to be static.

Joaquín M López Muñoz
Telefónica, Investigación y Desarrollo

Re: I'm doing similar but why won't work

24-May-02 4:39

I tried, but still the same.

Re: Holding pointers to functions as values in a std::map

Vivek Rajan24-May-02 7:54

Vivek Rajan

24-May-02 7:54

Alexpro wrote:

MyMap.insert (pair ("aaa", f1); // error here
and the error is

Be more type specific than pair(..)

Use this statement-

MyMap.insert(MyMap.value_type("aaa",f1));

HTH
Vivek

Change scrollbar colour

Nnamdi Onyeyiri24-May-02 1:23

Nnamdi Onyeyiri

24-May-02 1:23

hi, i have a CEdit control and I want to change the default scrollbars colour. i also do not want it to have the Winxp style on windows xp, but do not know how to do this.

My control is binded to a class called ECEdit, which is derived from CEdit, I want to put the code for he scrollbar in ECEdit.

==================================================
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Math and 3d books ?

Joao Vaz24-May-02 1:04

Joao Vaz

24-May-02 1:04

Someone could advise a good math or 3D book , considering that my math is weak (I didn't give a damn on college) .
It have to prepare me to do full blow 3d programming and learning first the basics then the more advanced math concepts.

Anyone had read these this books ? Are they good ?
Mathematics for 3D Game Programming & Computer Graphics
3D Graphics Programming: Games and Beyond

Thanks

Cheers,
Joao Vaz
A person who is nice to you, but rude to the waiter, is not a nice person - Natalie Portman (Padme/Amidala of Star Wars)

Re: Math and 3d books ?

jan larsen24-May-02 2:56

jan larsen

24-May-02 2:56

I have read 3D Graphics Programming: Games and Beyond, but i don't think that i really got anything usefull from it.

I also read the much too tiny chapter on 3D in the "black art of Java Game Programming", and it actually gives a better overall description to get you started (and it has an OOP view as opposed to the other book which uses C).

But what really helped was the tutorials in basic vector math that my girlfriend paced me through, and these links:
http://chortle.ccsu.ctstateu.edu/vectorLessons/vectorIndex.html
and
http://members.tripod.com/gamecode/tut/

The first link is the best tutorial on math that i ever saw besides my girlfriends tutorial (and you can't have her, she's MINE!).
The second link points to some implementation guides that are only helpfull when you understand the basics.

Some books tell you that "it really isn't nescessary to understand the math behind this, just use the formulas in good health", don't buy it!.
When you understand the math your'e seeing it all so much clear.

"It could have been worse, it could have been ME!"

Re: Math and 3d books ?

Joao Vaz24-May-02 3:21

Joao Vaz

24-May-02 3:21

Thanks Jansen for the links, they appear to be cool Smile | :)

jan larsen wrote:
I have read 3D Graphics Programming: Games and Beyond, but i don't think that i really got anything usefull from it.

Risking this book from the wishlist ... next ...

jan larsen wrote:
besides my girlfriends tutorial (and you can't have her, she's MINE!).

You jealous guy Poke tongue | ;-P

jan larsen wrote:
When you understand the math your'e seeing it all so much clear.

Yeap, that was my intention , to really understand the math , I don't like books that throw things at me without explanation ...

Thanks again , Jansen Smile | :)

Cheers,
Joao Vaz
A person who is nice to you, but rude to the waiter, is not a nice person - Natalie Portman (Padme/Amidala of Star Wars)

Re: Math and 3d books ?

C^hris L^osinger24-May-02 3:06

C^hris L^osinger

24-May-02 3:06

Foley and Van Damme's book on graphics is one of the standards. it does 2d, 3d, ray tracing, fractals, etc..

-c

Cheap oil. It's worth it!

ISEffects - effects for images

Re: Math and 3d books ?

Joao Vaz24-May-02 3:24

Joao Vaz

24-May-02 3:24

C^hris L^osinger wrote:
Foley and Van Damme's book on graphics is one of the standards

Okay , it so appears Smile | :)

Adding it to wishlist .... done ... 100% processed

Thanks Chris Smile | :)

Cheers,
Joao Vaz
A person who is nice to you, but rude to the waiter, is not a nice person - Natalie Portman (Padme/Amidala of Star Wars)

Calculation?

Zizilamoroso23-May-02 23:54

Zizilamoroso

23-May-02 23:54

LONG first = 1022230205L;
LONG second = 1000L;

LONG third = first * second;

cout << third << endl;

This should result in 1022230205000 but it returns 27988552 instead. Am I missing something here?

I've tried DWORD also, same result.

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Re: Calculation?

markkuk24-May-02 0:07

markkuk

24-May-02 0:07

The largest LONG is 2147483647, so your calculation causes an overflow.

Re: Calculation?

Zizilamoroso24-May-02 0:07

Zizilamoroso

24-May-02 0:07

Could be something like that. But I've tried DWORD as well.

I thought that the maximum was 9.223.372.036.854.775.807
The maximum you gave is for integers, no?

Can a long be negative?

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Re: Calculation?

Joaquín M López Muñoz24-May-02 0:24

Joaquín M López Muñoz

24-May-02 0:24

The maximum value of a DWORD is 4,294,967,295. You're having an overflow.

Joaquín M López Muñoz
Telefónica, Investigación y Desarrollo

Re: Calculation?

Zizilamoroso24-May-02 0:27

Zizilamoroso

24-May-02 0:27

Sorry guys.

I've noticed that a long only uses 4 bytes.

I'm a java programmer and a long is 8 bytes in java OMG | :OMG:

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Re: Calculation?

Nnamdi Onyeyiri24-May-02 0:07

Nnamdi Onyeyiri

24-May-02 0:07

why have you put an L at the end of the numbers? could that be the problem?

==================================================
When Your Mind Wonders...Where Does It Go???

Re: Calculation?

Zizilamoroso24-May-02 0:09

Zizilamoroso

24-May-02 0:09

If you don't put the L, the compiler assumes that's an integer. We add the L to reserve a bigger memzone.

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Re: Calculation?

Nnamdi Onyeyiri24-May-02 0:17

Nnamdi Onyeyiri

24-May-02 0:17

oh...didnt know that

==================================================
When Your Mind Wonders...Where Does It Go???

Re: Calculation?

KarstenK24-May-02 0:37

KarstenK

24-May-02 0:37

I don´t think that the L will reserve a bigger memzone. Unsure | :~

It only says the compiler that the number is to been seen as long, a typ-cast.

Try to trace every variable after assign it!!

Re: Calculation?

Matt Gullett24-May-02 0:29

Matt Gullett

24-May-02 0:29

You've overflowed the LONG. Try __int64.

Re: Calculation?

Zizilamoroso24-May-02 0:30

Zizilamoroso

24-May-02 0:30

Why do all the languages take there very own amount of bytes for the data types? java-long=8 <-> c++long=4 ...

Very confusing Mad | :mad:

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Re: Calculation?

Joaquín M López Muñoz24-May-02 0:32

Joaquín M López Muñoz

24-May-02 0:32

Type sizes in C++ are implementation-dependant. The standard only dictates the minimum size. However, for most (all?) 32-bit compilers, sizes are just like in VC++.

The next version of C++ standard most likely will include types with fixed size, like int32, int64 etc., to aid in the developing of cross-platform code.

Joaquín M López Muñoz
Telefónica, Investigación y Desarrollo

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