Managed C++/CLI

looping through strings C++ .NET

31-Mar-06 23:00

Hi,

for example:

if(args->Length > 0)
{
if(args[1]) // optionally, but first check the boundaries of that array; otherwise an "array out of bounds exception" will occur
DoFoolishThings(args[1]);
}

regards Tobias

richiebaby31-Mar-06 4:05

richiebaby

31-Mar-06 4:05

Hello all,

I'll start by saying the dreaded words: I am a newbie.

Started using visual studio .NET recently and I just can't seem to do anything with it. I am used to visual studio 6 c++ and I'm having difficulty with the transition.

Under .NET I have creeated a rich text box that I would like to use to display a string of text. The difficulty arises because each character within the string can have different formatting applied (bold, italic, underline). So I would like to simply step through each character within the string and output them one-by-one.

My C++ brain tells me that I would like to simply use a for_each, like this:

<br />
   string s = "Hello I am a test string";<br />
   for_each(s.begin(), s.end(), printValue);<br />

So can anyone explain what would be different when implementing the above functionality within .NET,
or can I still somehow write the same C++ that I am used to?

Just to give an idea, here is a code snippet

<br />
private: System::String *text_string;<br />
<br />
private: System::Void outputToScreen()<br />
{<br />
   this->text_string = S"Hello I am a test string...";<br />
<br />
   //This is where I would like to perform a for_each (or equivalent)<br />
}<br />

Even links to relevant API support documentation would be great

Thanks for your help.

Re: looping through strings C++ .NET

Saksida Bojan31-Mar-06 5:34

Saksida Bojan

31-Mar-06 5:34

richiebaby wrote:
Started using visual studio .NET

Witch one: 2003 or 2005. I will use 2005 syntax for samples.

richiebaby wrote:
My C++ brain tells me that I would like to simply use a for_each, like this:

Your sample is wrong.
String has simular behaver like CString.

using namespace System;
using namespace System::Collections;

int main(array<System::String ^> ^args)
{
	String ^s = gcnew String("Hello, I am a test String");
	array <Char> ^sChars = s->ToCharArray();
	IEnumerator ^myEnum = sChars->GetEnumerator();
	while (myEnum->MoveNext())
	{
		String ^ss = (myEnum->Current->ToString());
		Console::WriteLine("-{0}-", ss);
	}
    return 0;
}

Re: looping through strings C++ .NET

richiebaby31-Mar-06 5:51

richiebaby

31-Mar-06 5:51

Hi
Thanks for your help, but I'm afraid that I need a little more guidance.

First the answer to your question: I am using .NET 2003.

Some more info: I started a new Windows form project, I then proceeded to create a RichTextBox on the form. So setting the text is easy but I am trying change the font of individual characters within the RichTextBox(don't know if the best solution is to use RichTextBox or not).
So I figured that I would go through each char within the string, apply a font and append to the contents of the RichTextBox (not even sure if possible).

The trouble is I can't seem to get to grips with the .NET framework, I find it harder than good old C++.

Straight away I am slightly lost with your sample code, how can I take your suggested code and import it into the code that .NET has produced for me. Bearing in mind I am not within the main method but within a new that I have created.

For instance, if I have an empty method called outputToScreen(), how can I even start to use your suggested code.

<br />
private: System::Void outputToScreen()<br />
{<br />
<br />
}<br />

If I write:

<br />
private: System::Void outputToScreen(array ^args)<br />
{<br />
}<br />

Then I get "error C6201: syntax error : identifier 'array'"

These are probably dumb question but i am trying to learn, so...

Thank you.

Re: looping through strings C++ .NET

Saksida Bojan31-Mar-06 6:51

Saksida Bojan

31-Mar-06 6:51

richiebaby wrote:
Thanks for your help, but I'm afraid that I need a little more guidance

Sure, that's whay we are here.

richiebaby wrote:
First the answer to your question: I am using .NET 2003.

It was a long time ago when i used VS2003.

Some syntax diffrences betwen VS2003 and VS2005 (List is incomplete
VS2003						VS2005
new						gcnew
__gc						(In gc container, you don't use it)
* (pointer def.)				^
(String *sArray = new String __gc *[10];	array (defin. for ar.)

VS2003 using managed c++(obsolete syntax). VS2005 is using newer syntax called C++/CLI. Currently i have vs2005 installed, so i can't garanity, that my code is bug free.

richiebaby wrote:
Straight away I am slightly lost with your sample code, how can I take your suggested code and import it into the code that .NET has produced for me. Bearing in mind I am not within the main method but within a new that I have created.

you can use it as find the position. But it is VS2005 syntax, i forgot how it look like in VS2003.

richTextBox1->Text = "Hello, World.";	// Displays Text
richTextBox1->Select(7,5);	// Select Chars, Starting in 7th pos. and 5 chars
richTextBox1->SelectionFont = new System::Drawing::Font("Tahoma", 12, FontStyle::Bold);	// Set Font Name, size and style
richTextBox1->SelectionColor = System::Drawing::Color::Blue;	// Set a color.
richTextBox1->DeselectAll();	// deselect a sellection

You can sceep command Select(int, int), SelectAll() and DeselectAll(), if you intend to select a text with a mouse.

richiebaby wrote:
The trouble is I can't seem to get to grips with the .NET framework, I find it harder than good old C++.

Because you are used to. I couldn't learn c++ (MFC and Win32) is due to an problems with converting from one to another parameter. In .NET i could Use like String::ToInt32(S"666");

Re: looping through strings C++ .NET - Figured it out

richiebaby31-Mar-06 6:54

richiebaby

31-Mar-06 6:54

After a bit of hacking I have found a working solution.

Many thanks to the person who posted their code.

Here is a copy of what I was trying to achieve

<br />
private: System::Void outputToScreen()<br />
{<br />
  //Must clear the contents of the textBox for each repaint<br />
  textBox->Clear();<br />
<br />
  //New temp string for use within while loop<br />
  System::String *temp_text_string;<br />
				<br />
  //Initialise text_string<br />
  text_string = S"Hello I am a test string";<br />
				<br />
  //Declare an array, call it stringArray<br />
  Array *stringArray;<br />
 <br />
  //Fill stringArray with contents of text_string<br />
  stringArray = text_string->ToCharArray();<br />
<br />
  //Not sure what this does<br />
  IEnumerator *myEnum = stringArray->GetEnumerator();<br />
<br />
  //Loop through myEnum<br />
  while (myEnum->MoveNext())<br />
  {<br />
    //Initialise new_text_string with current value<br />
    temp_text_string = (myEnum->Current->ToString());<br />
		<br />
    //Setup up the font (currently the same for all chars - need to create another array)<br />
    textBox->SelectionFont = new System::Drawing::Font( "Arial",12,FontStyle::Italic );<br />
<br />
    //Output to richTextBox ("textBox")<br />
    textBox->SelectedText = temp_text_string;<br />
  }										<br />
<br />
}<br />

So there we have it, I am much happier now that I have something to work on.

I know it's ugly but I'm happy seeing as I've only used .NET for less than 48 hours.

Thanks again

Very strange error

Joel Holdsworth30-Mar-06 11:58

Joel Holdsworth

30-Mar-06 11:58

I have this very wierd error message in Visual C++ Express 2005:

1>.\UIEvents.cpp(252) : error C2860: 'void' cannot be an argument type, except for '(void)'
1>        This diagnostic occurred while importing type 'VLCWPF::SkinInterface::PlaylistItem ' from assembly 'VLCWPF, Version=0.0.0.0, Culture=neutral, PublicKeyToken=null'.

Here's the offending code:

InputItem *inputitem = item->get_InputItem();

What's most wierd to me is that I can't find anywhere where this mysterious void could be coming from. The class InputItem is very simple, so I can't see why it would have problems:

public class InputItem
{
    public InputItem(string name, string uri, string[] inputOptions, int id, InputInterface.InputType inputType)
    {
        this.name = name;
        this.uri = uri;
        this.inputOptions = inputOptions;
        this.id = id;
        this.inputType = inputType;
    }

    public InputItem(string name, string uri) :
        this(name, uri, null, 0, InputInterface.InputType.Unknown)
    {

    }

    public string Name
    {
        get { return name; }
        set { name = value; }
    }

    public string Uri
    {
        get { return uri; }
        set { uri = value; }
    }

    protected string name;
    protected string uri;
    protected string[] inputOptions;
    protected int id;
    protected InputInterface.InputType inputType;
}

Can anyone make any suggestions? I can't figure out for the life of me what could cause this.

Joel Holdsworth

George L. Jackson30-Mar-06 17:10

George L. Jackson

30-Mar-06 17:10

First of all, your InputItem class looks like C#. Assuming the class is located in a C# assembly, your problematic code should look like something like this:

InputItem ^inputitem = item->get_InputItem();

The "*" is for unmanaged code.

Saksida Bojan30-Mar-06 18:11

Saksida Bojan

30-Mar-06 18:11

George L. Jackson wrote:
The "*" is for unmanaged code.

And for old Managed c++

George L. Jackson31-Mar-06 1:01

George L. Jackson

31-Mar-06 1:01

I almost forgot! The "get_" in "item->get_InputItem()" may also be a problem!

Transfer Data from SQL Database to DataTable

John L. DeVito30-Mar-06 23:11

John L. DeVito

30-Mar-06 23:11

You're using 2 different languages here. I don't know that C# has a dereference operator, except in unsafe blocks.

Thanks,
John

kevin12730-Mar-06 4:45

kevin127

30-Mar-06 4:45

Hi All,

I am using VC++ 2005 Express and SQL Server express. The database MyDB has shown in the Data Sources panel after applying "add new data source" steps. In the MYDB, there is a table called "MyTable", which is also shown in Data Sources panel. How do I transfer data from MyTable to a DataTable ("dtTable")? I tried following codes but it didn't work.

SqlDataAdapter^ sqlAdapter;
DataTable^ dtTable;
sqlAdapter = gcnew sqlDataAdapter("select * from MyTable", "MyDB");
dtTable = gcnew DataTable("dtTable");
sqlAdapter->Fill(dtTable);

Any suggestions? Thanks in advance.

Kevin

Re: Transfer Data from SQL Database to DataTable

George L. Jackson30-Mar-06 16:49

George L. Jackson

30-Mar-06 16:49

I don't see any connection string or code to talk to the database! Confused | :confused:

Re: Transfer Data from SQL Database to DataTable

kevin12730-Mar-06 18:18

kevin127

30-Mar-06 18:18

Thanks George. I thought that, when a database was shown in the Data Sources panel, the connection codes were implied. I'll add connection codes and try again.

Kevin

Copying array values into a managed structure

Sangeetha.R30-Mar-06 0:14

Re: Copying array values into a managed structure

30-Mar-06 0:14

Hi,
I do have the following structure in vc++

public ref struct structExample
{
int a;
char b;
float c;
};

i need to copy the array of bytes value into this structure,
Generally if the structure is not a managed type we use "memcpy()" to copy the contents into the structure.
Similarly how can be done this ,in case of managed structures

Thanks in advance
Sangeetha

2bee 30-Mar-06 1:45

Re: Copying array values into a managed structure

30-Mar-06 1:45

Hi,

basically the BitConverterClass should meet your requirements. But most likely there is a more elegant way to do this.

e.g.

structExample^ strEx = gcnew structExample();

strEx->a = BitConverter::ToInt32(byteArray,indexofyourinteger);

regards Tobias

Sangeetha.R30-Mar-06 18:18

Re: Copying array values into a managed structure

30-Mar-06 18:18

I need to copy the array elements into the structure on a whole at a stretch as "memcpy()" does in ummanaged code, since I do have 100 elements/members in the structure.

2bee 30-Mar-06 19:31

Checking For Null while rasing the events

30-Mar-06 19:31

Well you can either use serialize/deserialize on your struct or you could actually use one of these methods:

Marshal::PtrToStructure(...);<br />
Marshal::StructureToPtr(...);

Please note that those methods marshal data from a managed object to an unmanaged block of memory and vice versa. Further information is also provided here:

http://www.dotnet247.com/247reference/msgs/57/289239.aspx[^]

regards Tobias

Sangeetha.R30-Mar-06 0:03

30-Mar-06 0:03

Hi,

I want to raise an event from my code in vc++.
while raising the event i need to check for the null.
Basically to know whether some one has registered for this event . How the event can be checked for the Null value.
if it is not checked System::NullReference Exception is thrown

thanks in advance,
Sangeetha

Milton Karimbekallil30-Mar-06 4:08

Milton Karimbekallil

30-Mar-06 4:08

try if ( event == nullptr )

rgds...mil10.

Sangeetha.R30-Mar-06 21:18

30-Mar-06 21:18

This gives the error as follows
error C3918: usage requires 'event' to be a data member

Regards
Sangeetha

Milton Karimbekallil31-Mar-06 1:54

Milton Karimbekallil

31-Mar-06 1:54

seems u have no declared the evenet object properly. Please post the code.

rgds...mil10.

2bee 31-Mar-06 3:17

31-Mar-06 3:17

Hi,

i discovered a while ago the same error and found this here quite useful:

http://forums.microsoft.com/MSDN/ShowPost.aspx?PostID=3059&SiteID=1[^]

Basically this behaviour is by design and a check for null is not neccessary. However, here is another explanation why.

http://lab.msdn.microsoft.com/productfeedback/viewfeedback.aspx?feedbackid=ac4f8e6b-c5eb-4ad0-9585-2fd0542a06aa[^]

regards Tobias

Sangeetha.R2-Apr-06 18:44