Re: how to declare array of object - Managed C++/CLI Discussion Boards

Re: System::String ^ to LPCWSTR conversion?

Mark Salsbery7-Jan-10 12:56

Mark Salsbery

7-Jan-10 12:56

Mattzimmerer wrote:
I cannot get the contents of ProcNameWSTR to match my tester[11]

ProcNameWSTR is a single wchar_t, so isn't very useful here.
Plus you don't even use it anywhere.

Marshal::StringToHGlobalUni returns a const pointer to a wchar_t
string, so casting it to a char* then converting it to a wchar_t
string isnt' going to work.

Try:

const wchar_t *pProcNameWSTR = (const wchar_t *)(void *)Marshal::StringToHGlobalUni(this->ProcName->Text);

Mark Salsbery
Microsoft MVP - Visual C++
Java | [Coffee]

Re: System::String ^ to LPCWSTR conversion?

Mattzimmerer7-Jan-10 22:01

Mattzimmerer

7-Jan-10 22:01

worked great thank you. You know, I tried something like this, I just didnt make it a const, perhaps thats the reason it didnt work... Either that or I threw in some ANSII.. o well thanks man!

How to Get DataTable column name ?? [modified]

ajaxswan6-Jan-10 18:18

ajaxswan

6-Jan-10 18:18

HI

I have DataTable n there is 5 column I had created

I want to get 5 column name and column data type from my datatable to create slq query

"Create Table mytable ([from datatable column name and type 1 to 5 ])"

how to do it ???

thanks

modified on Thursday, January 7, 2010 12:24 AM

Re: How to Get DataTable column name ??

Andreoli Carlo19-Jan-10 2:30

Andreoli Carlo

19-Jan-10 2:30

First of all this doesn't sound like a good question
all you are asking is really simple to do, too simple to ask in this forum. Maybe it would be good for you to study an introductory book to this language D'Oh! | :doh:

i didn't get you real problem but here some hint....

// to get the column number
dataGridView1->Columns->GetColumnCount

// to get the colum name (from column number i)
dataGridView1->Columns[i]->Name

// to get the column value type (from column number i)
dataGridView1->Columns[i]->ValueType

how to declare array of object [modified]

m_mun6-Jan-10 1:02

m_mun

6-Jan-10 1:02

Hi,
Suppose I have a class named "Bounce". How can i declare array of objects in another class using managed c++?

Thanks to all

modified on Wednesday, January 6, 2010 7:09 AM

Re: how to declare array of object

Luc Pattyn6-Jan-10 2:51

Luc Pattyn

6-Jan-10 2:51

Did you try anything at all?
What is your book telling you?

I would try something similar to:

array < String ^ > ^ tab=gcnew array < String ^ > (200);

Luc Pattyn [Forum Guidelines] [Why QA sucks] [My Articles]

Happy New Year to all.
We hope 2010 soon brings us automatic PRE tags!
Until then, please insert them manually.

Re: how to declare array of object

Dave Doknjas6-Jan-10 11:45

Dave Doknjas

6-Jan-10 11:45

It's far more common these days to use a generic list, such as System::Collections::Generic::List.

List<bounce> ^ myList = gcnew List<bounce>();

Removing and inserting is easier this way.

David Anton
Convert between VB, C#, C++, & Java
www.tangiblesoftwaresolutions.com

Re: how to declare array of object

SteelModule28-Jul-10 5:06

SteelModule

28-Jul-10 5:06

Hello, I have another problem:

I would like to use ArrayList for collecting of unknown number of System::Drawing::Point structures. But I´m not able to use it in some GDI+ drawing functions feg. Graphics::DrawCurve(...). It forces me to use cli::array<point>, it is totally ugly, I ended up with something like this:

// Dynamic array
ArrayList^ arr = gcnew ArrayList;
// Add some test data
arr->Add(Point(0, 0));
arr->Add(Point(25, 25));
arr->Add(Point(50, 75));
arr->Add(Point(75, 100));
.
.
arr->Add(Point(225, 325));

// Somewhere prior drawing...
array<Point>^ pt = gcnew array<Point>(arr->Count);
for(int i = 0; i < arr->Count; i++)
  pt[i] = (Point)arr[i];

// Actual drawing...
g->DrawCurve(pen, pt);

It works, but... Is there a better way to do something like this? I'm sure I'm wrong, but I learn C++/CLI about an hour Smile | :)

. There are no such problems if I use GDI+ in Win32 API, MFC...

Re: how to declare array of object

Dave Doknjas28-Jul-10 5:20

Dave Doknjas

28-Jul-10 5:20

Use a list and it's 'ToArray' method:
List<point>^ arr = gcnew List<point>();
g->DrawCurve(pen, arr.ToArray());

David Anton
Convert between VB, C#, C++, & Java
www.tangiblesoftwaresolutions.com

Re: how to declare array of object

SteelModule28-Jul-10 21:49

SteelModule

28-Jul-10 21:49

Thank you for a fast reply, it helped. Smile | :)

Actually I have found ToArray() function previously, I used it (but with ArrayList) in trials with both C# and C++/CLI, but it doesn't compile in C++/CLI, I got error C2664. In C# I was able to cast it, it does compile and work, not so in C++.

Btw., it still copies one array into another as I did, it looks much more clean, but again not very efficient... Dead | X|

I used to write same app in C# and C++/CLI for learning, to see, which .NET code will look better for me. I use native C/C++/ASM long time professionaly, I work as a lead programmer on a big, well known engineering computational SW package, written mainly in native C++. It has an extensive GUI (our boss is GUI guy Suspicious | :suss:

), which we would like to port to some C family .NET language, maybe with WPF.

DATASET to sqlite.net

ajaxswan4-Jan-10 15:38

ajaxswan

4-Jan-10 15:38

hi

can anyone can help me i'm trying to insert my dataset or datatable into
sqlite.net

and I don't have any clue

can anyone create some sample ??? with c++ clr form

thanks

System::String ^ to LPCVOID conversion? [modified]

Mattzimmerer2-Jan-10 10:42

Mattzimmerer

2-Jan-10 10:42

Im trying to use WriteFile() to communicate with a driver, the information its sending is to be text from a Windows Forms textbox. I've tried so much to get it to work properly but it only seems to work if I do the following for WriteFile():
WriteFile(hFile, "this is the only way it works", sizeof("this is the only way it works");, &dwReturn, NULL);

Im pretty lost and I would appreciate any help!
Heres what my code looks like:

System::String ^str = this->Address->Text; //ANOTHER QUESTION.. WHATS THE ^ mean before str? Or where can I read about this operator?
LPCVOID lpBuffer = str;
/*BOOL WINAPI WriteFile(
	__in         HANDLE hFile,
        __in         LPCVOID lpBuffer,
        __in         DWORD nNumberOfBytesToWrite,
        __out_opt    LPDWORD lpNumberOfBytesWritten,
        __inout_opt  LPOVERLAPPED lpOverlapped			);*/
WriteFile(hFile, lpBuffer, sizeof(lpBuffer), &dwReturn, NULL);
CloseHandle(hFile);

and the compiler output:
1>c:\users\matt_zimmerer_testos\desktop\zmdalpha1.0\gui\zmdinterface\Form1.h(170) : error C2440: 'initializing' : cannot convert from 'System::String ^' to 'LPCVOID'

EDIT: minor grammar error fixed

modified on Saturday, January 2, 2010 5:06 PM

Re: System::String ^ to LPCVOID conversion?

Richard MacCutchan2-Jan-10 22:04

Richard MacCutchan

2-Jan-10 22:04

System::String is a managed type and needs to be converted to a character array before you can cast it to a simple pointer. Take a look at the System::String[^] class, for more information.

coding help

helawae31-Dec-09 19:52

helawae

31-Dec-09 19:52

Hi,
i am looking for help in implementing a thesaurus application for a data structure project, but have trouble in finding the best data structure to represent the thesaurus, also if anybody could direct me in how to start the coding in C++ or C# would be a great help.
1. i have so far considered trees and linked lists as a possible solution, the tree for storing the words and the linked list for returning the set of synonyms but i do not know how to store the words in the tree for best searching and how to link up the tree with the linked list..
so any help or pointers would be a great help

Re: coding help

N a v a n e e t h1-Jan-10 3:03

N a v a n e e t h

1-Jan-10 3:03

helawae wrote:
best data structure to represent the thesaurus,

Are you trying to represent the whole thesaurus in memory?

helawae wrote:
i have so far considered trees and linked lists as a possible solution, the tree for storing the words and the linked list for returning the set of synonyms but i do not know how to store the words in the tree for best searching and how to link up the tree with the linked list..

Tree and linked lists seems to be good choice. Each node represents a term and contains a list of related terms. This can nest up to any level. However, keeping the whole thesaurus in memory and searching in it is quite inefficient. I'd suggest to keep the data in a database and query against it when you need a lookup. Load the term and related terms into the above said data structure and return. You can load each level of this tree on demand. So you will not waste any memory by storing data that you don't need.

helawae wrote:
direct me in how to start the coding in C++ or C# would be a great help.

Take a look at file based databases like SqlLite. Create relational tables and keep the data inside it. Probably two tables, one is the master list of all terms and second one is the relationships. When you need to do a lookup, join both tables and get the data.

Hope that helps

Smile | :)

Best wishes,
Navaneeth

Re: coding help

helawae3-Jan-10 21:56

helawae

3-Jan-10 21:56

hey thanks for the last reply, it was helpful but there are somethings i still do not understand(sorry!)
1. When you say "keeping the whole thesaurus in memory and searching in it is quite inefficient. I'd suggest to keep the data in a database and query against it when you need a lookup. Load the term and related terms into the above said data structure and return"

if searching in memory is inefficient and keeping the data in a database and query against it whenever i need a look up say for example i have one table with the root words(words that are stored in the tree nodes) and another table storing the synonyms(the words maintained in the linked list) and an associated foreign key representing the words in the first table is stored with each words in the second table then why do i need to return the result of the query to the above data structure why can i not simply display the results of the query to the user directly!

2.What is meant when you say "You can load each level of this tree on demand".

I thought of using two structs like
Struct RootTree{
RootTree* Node;
string word;// the actual words stored in the tree
SynList * pointer;// a pointer to the linked list maintaining the //synonyms
}
Struct SynList(
SynList* Nod;
string syns;
synList* pointer;// a pointer to the next Nod in the linked list
)
Now how do i nest this to several levels and where is the actual search implemented in the database or in the structs!
thank you again!

Re: coding help

N a v a n e e t h7-Jan-10 18:06

N a v a n e e t h

7-Jan-10 18:06

helawae wrote:
why can i not simply display the results of the query to the user directly!

Possible. But by populating the data structure helps you to do caching and return results from the cache when user searches for the same term again. Do what makes best sense for your problem. But don't ever try to keep the whole data in memory.

helawae wrote:
What is meant when you say "You can load each level of this tree on demand".

Ignore that. You should be good with the other things what I explained. Implement demand loading only when it requires.

Smile | :)

Best wishes,
Navaneeth

Re: coding help

helawae9-Jan-10 20:41

helawae

9-Jan-10 20:41

hey thanks for the whole help!It has been really useful. i have solved the problem and the thesaurus is finished! i used a trie structure instead of the linked list and tree, like u have pointed out i have kept the whole data in the database and retrieved information from it when only the user types in the words. thanks again for all the help!

Re: coding help

N a v a n e e t h10-Jan-10 3:11

N a v a n e e t h

10-Jan-10 3:11

Glad to hear that. Thumbs Up | :thumbsup:

Best wishes,
Navaneeth

VC C++ 2005 Error Create Register in clr form

ajaxswan27-Dec-09 16:12

ajaxswan

27-Dec-09 16:12

hi ,

I'm New In C++ FORM crl Programing
I Want to Register Data to registry
I check Sample Code in MSDN
like this :

RegistryKey ^ regkey = Registry::LocalMachine->CreateSubKey("SOFTWARE\MYSOFTWARE\DATA");

And I got no error and 2 warning

11>------ Build started: Project: MULTINET_EXPLORER, Configuration: Debug Win32 ------
1>Compiling...
1>MULTINET_EXPLORER.cpp
1>d:\multinet explorer\multinet_explorer\Form1.h(222) : warning C4129: 'M' : unrecognized character escape sequence
1>d:\multinet explorer\multinet_explorer\Form1.h(222) : warning C4129: 'M' : unrecognized character escape sequence
1>Linking...
1>Embedding manifest...
1>Build log was saved at "file://d:\MULTiNET EXPLORER\MULTINET_EXPLORER\Debug\BuildLog.htm"
1>MULTINET_EXPLORER - 0 error(s), 2 warning(s)
========== Build: 1 succeeded, 0 failed, 0 up-to-date, 0 skipped ==========

but when the program runing it always gon error message

like this
An unhandled exception of type 'System.IO.IOException' occurred in mscorlib.dll

Additional information: The parameter is incorrect.

how can I solve this Problem ???

can anyone help me ???

Re: VC C++ 2005 Error Create Register in clr form

Luc Pattyn28-Dec-09 1:26

Luc Pattyn

28-Dec-09 1:26

Hi,

in C-like languages string literals treat backslash as a special character; the character following it determines the exact meaning (e.g. \t represents a TAB). To get a simple backslash, you should double it: "SOFTWARE\\MYSOFTWARE\\DATA"

I would suggest you buy and study a book on C++/CLI to get the fundamentals right.

Smile | :)

Luc Pattyn [Forum Guidelines] [Why QA sucks] [My Articles]

Merry Christmas and a Happy New Year to all.

Syncronize Two ComboBox in visual c++

johnjitu22-Dec-09 23:40

johnjitu

22-Dec-09 23:40

Hello

Dear friends

I am stuck with this problem of combobox.It is proyect of Visual c++,i have two comboboxes ,my task is to select one item from one combobox ,and the item corresponding to this in the other combobox will select automatically.

Merry christmas and Happy new year

waiting for your kind help

Re: Syncronize Two ComboBox in visual c++

N a v a n e e t h23-Dec-09 20:08

N a v a n e e t h

23-Dec-09 20:08

Assuming you are using C++/CLI. Handle the first combo box's SelectedIndexChanged[^] event and populate the second one accordingly.

Best wishes,
Navaneeth

C# send structure objects through socket

ikurtz18-Dec-09 6:03

ikurtz

18-Dec-09 6:03

i have done a bit of reading in client/server programming in c#. i am familiar enough with this process to ask the following question:

how do i transmit structure objects through tcp/ip instead of just strings?

my app is a networked game with chat capabilities. so instead of just transmitting text, i would like to imploy a data structure or class structure that will have two fields: i. packet type ii. the data for the packet type

and i would transmit this when needed during the execution of the application, and decode the data object at the receiving end and place it where it belongs.

im not looking for code, just some ideas and search statements i can feed to google so i will; have a better understanding.

ive read about serialisation/de serialisation, is that he way to go?

thanks.

Re: C# send structure objects through socket

Paulo Zemek18-Dec-09 8:29

Paulo Zemek

18-Dec-09 8:29

See serialization and deserialization of objects.
I use BinaryFormatter for this job.

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