C / C++ / MFC Discussion Boards

Nemanja Trifunovic19-Jul-07 3:15

19-Jul-07 3:15

It's legal. text first points to an empty string, and then to a "hello".

Just don't attempt to change the string that text is pointing to Smile | :)

Programming Blog
utf8-cpp

Re: Back to the roots

James R. Twine19-Jul-07 3:17

James R. Twine

19-Jul-07 3:17

   IMHO, it is kinda legal - constant strings usually use constant memory, but you are assigning them to a non-const pointer.

   That code will compile on lots of compilers, if that means "legal" to you.

   Remember that a pointer and an array are two different things - a pointer points to a location in memory (which may or may not be valid), while an array IS a valid location in memory.

   Since your pointer is not set up (initially) to point to any valid memory, you could not strcpy(...) into it without risking a crash or other problems.

char *text;
text=""; // Valid
text="hello"; // Valid
// ------
char *text;
strcpy( text, "some string" ); // NOT Valid - no valid memory pointed to by <code>text</code>
// ------
char textarray[ 64 ];   // A valid array
char *text = textarray; // Valid, pointer now points to a valid array
 
strcpy( text, "some string" ); // Valid - string written into memory pointed to by <code>text</code> (which is the <code>textarray</code> array)
strcpy( textarray, "another string" ); // Valid - arrays "degrade"/"decay" into pointers, so the string is written into the <code>textarray</code> array

Peace!

-=- James
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Re: Back to the roots

Rage19-Jul-07 3:23

Rage

19-Jul-07 3:23

Oh yes, that's it. Thanks James.

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[RT]

Eytukan19-Jul-07 8:15

Eytukan

19-Jul-07 8:15

Related topic! Ofcourse another "root"

James, Imagine I'm initializing a char-string array statically like :

char chArray[MAX_LEN][MAX_LEN]={"ONE","TWO","THREE".....};
This being declared/defined globally makes no issues. Now I want this be wrapped up inside a class. and still wanting to do it in a single line. like the above. You cannot certainly init it inside a class' declaration.

and if you take this to the constructor, you would lose the declaration(data memeber!) inside the class. so how to go? Should I use refs inside the constructor? Unsure | :~

Best wishes to Rexx[^]

Re: [RT]

James R. Twine19-Jul-07 8:47

James R. Twine

19-Jul-07 8:47

VuNic wrote:
char chArray[MAX_LEN][MAX_LEN]={"ONE","TWO","THREE".....};

That still creates a single linear block of memory, and the indexes are just calculations to index into it. So you can still allocate all of it in one shot (size == MAX_LEN * MAX_LEN), and still use multiple bracket operators to get specific memory locations and initialize those locations. You could (theoritically) initialize all of those locations them on a single line, although not a single statement. Smile | :)

   But then again I might not be understanding your question correctly...

   If you need to "hide" access to chArray, you can place it into a namespace and then have the class manipulate it in that namespace...

   Peace!

COM Object Registration!

sachinjegaonkar19-Jul-07 2:17

sachinjegaonkar

19-Jul-07 2:17

I want to know, after registration of COM server object to windows and if i want to ship that object to other machine, whether that object will carry registration information(e.g. CLSID registered with that object) or not?
If it is not carring this information then is another CLSID generated after i installs that object to other machine than the CLSID that of previous machine?

If it is true then how windows maintains GLOBAL UNIQUE IDENTIFIER for that COM object.

Re: COM Object Registration!

Nibu babu thomas19-Jul-07 2:39

Nibu babu thomas

19-Jul-07 2:39

sachinjegaonkar wrote:
GLOBAL UNIQUE IDENTIFIER

Here[^] is some information on this topic.

Nibu thomas
A Developer

Code must be written to be read, not by the compiler, but by another human being.

http:\\nibuthomas.wordpress.com

Re: COM Object Registration!

_AnsHUMAN_ 19-Jul-07 2:43

_AnsHUMAN_

19-Jul-07 2:43

A GUID comprises of information taken from the resources on your machine, however the algorithm for creating GUID's is criticized worldwide for the way it is implemented. Every machine has a network card MAC address. This network cards MAC address provides the basis of creation of GUID. Then the algorithm uses some other details to create a unique ID. The ID is itself not guaranteed to be unique but the probability of two ID's to be same is very low.
The CLSID does not change for a object from machine to machine. It remains the same.
I hope this helps you.

Somethings seem HARD to do, until we know how to do them.
Wink | ;-)

_AnShUmAn_

Re: COM Object Registration!

tanvon malik19-Jul-07 2:50

tanvon malik

19-Jul-07 2:50

Hi COM server's CLSIDs are inside them.
these CLSIDs are set with the COM server when it is developed.
So it is developers work, When any body installs a COM server
that CLSID which is embed inside the COM server is written in the
registry of the computer where that server is being installed.

tanvon malik
http://www.tanvon.com
http://tanvon.wordpress.com
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passing values from ui thread to view class

neha.agarwal2719-Jul-07 2:10

neha.agarwal27

19-Jul-07 2:10

Hello all i have made a sdi application having view derived from CFormView Class. In that class i have made a list control. I have also made ui thread which performs certain task and then has to return some CString and int values using which we fill our list control. now i want to know how do i pass these values to my list control class.

Can anybody please tell me the way with the code

thanks in advance...

Re: passing values from ui thread to view class

David Crow19-Jul-07 2:40

David Crow

19-Jul-07 2:40

neha.agarwal27 wrote:
now i want to know how do i pass these values to my list control class.

Allocate them on the heap in the view class. Pass that address to the thread.

"A good athlete is the result of a good and worthy opponent." - David Crow

"To have a respect for ourselves guides our morals; to have deference for others governs our manners." - Laurence Sterne

Re: passing values from ui thread to view class

neha.agarwal2719-Jul-07 2:46

neha.agarwal27

19-Jul-07 2:46

can you please tell me how to code for them...

Re: passing values from ui thread to view class

David Crow19-Jul-07 3:12

David Crow

19-Jul-07 3:12

See this article, about 1/4 way down.

"A good athlete is the result of a good and worthy opponent." - David Crow

"To have a respect for ourselves guides our morals; to have deference for others governs our manners." - Laurence Sterne

Re: passing values from ui thread to view class

Rage19-Jul-07 3:17

Rage

19-Jul-07 3:17

As David said:

Create your variables on the heap, using the new operator.

MyClass *a = new(MyClass);

Then, when you create your thread, pass the pointer (in this case *a) to the thread as an argument. After processing data in the thread, you can assign them to *a, and then close the thread.

http://www.readytogiveup.com/[^] - Do something special today.
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multiple selection in a list box

prithaa19-Jul-07 2:03

prithaa

19-Jul-07 2:03

Hello,

I have a list box using CListBox class in which I want to select multiple choices in the list box. But how do I get all the strings selected in an array.

The documentation of CListBox tehre is no function to get multiple strings.
The GetSelItems() function gives multiple ints then What should I do.

Thanks

Prithaa

Re: multiple selection in a list box

David Crow19-Jul-07 2:41

David Crow

19-Jul-07 2:41

prithaa wrote:
The GetSelItems() function gives multiple ints then What should I do.

Those are the indexes of the selected items.

"A good athlete is the result of a good and worthy opponent." - David Crow

"To have a respect for ourselves guides our morals; to have deference for others governs our manners." - Laurence Sterne

Re: multiple selection in a list box

prithaa19-Jul-07 3:01

prithaa

19-Jul-07 3:01