C / C++ / MFC

Newbie0016-Feb-07 4:19

Newbie00

16-Feb-07 4:19

You can edit Windows registry:

RootKey="HKEY_LOCAL_MACHINE"

OpenKey= "SOFTWARE\\Microsoft\\Windows\\CurrentVersion\\Run"

or

OpenKey= "SOFTWARE\\Microsoft\\Windows\\CurrentVersion\\RunOnce"
for running an application once at win startup

Add new REG_SZ value type, which data is the path for your application

I've tried it with Win 2000

Super Hornet16-Feb-07 4:50

Super Hornet

16-Feb-07 4:50

Thank you newbie its quite useful.

PJ Arends16-Feb-07 8:27

PJ Arends

16-Feb-07 8:27

You can also use the root HKEY_CURRENT_USER with the same keys if you want to limit the app to a specific user. Also avoids the security issues around apps not being able to write to HKEY_LOCAL_MACHINE.

You may be right
I may be crazy
-- Billy Joel --

Within you lies the power for good, use it!!!

Newbie0016-Feb-07 8:30

Newbie00

16-Feb-07 8:30

true

led mike16-Feb-07 4:55

led mike

16-Feb-07 4:55

Super Hornet wrote:
Is there any better way of running an application at windows startup?

Make it a Windows Service[^] There is a C++ Application Wizard that supplies a starter project for a Service.

led mike

strcpy giving exception

sanjutvm16-Feb-07 3:27

16-Feb-07 3:27

Hi,

I'm using MFC extension dll.

I've 2 questions.

1. Why do i get exception while trying this:

char* s1 = "";
char* s2 = abc";
strcpy(s1,s2); //exception

But if i try this it works:
char s1[255];
char* s2 = abc";
strcpy(s1,s2);

Why is this so?

2. I've an exposed function BOOL _stdcall SetName(CString& name)

There is a function defined in another class but in same dll as below.

void CMyClass::Myfn(CString& str)
{
m_str = str;
}

where m_str is CString variable declared in header and initialized as
m_str = "" in CMyClass constructor.

I create an object of CMyClass and call Myfn() in SetName.
SetName is called from a vb.net application.

I get exception while assigning m_str = str in Myfn();

(This works fine if i'm calling the dll from an MFC application.)

I solved the problem by making the following changes.
m_str declaration as char m_str[255] and removed initialization from constructor.
Myfn() as
void CMyClass::Myfn(char* str)
{
strcpy(m_str,str)
}

But how did it work? Will it create problem in anyother scenario?

Thanks & Regards,
sanju

toxcct16-Feb-07 3:45

toxcct

16-Feb-07 3:45

s1 has not enough space to write the content of s2 in it

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Cedric Moonen16-Feb-07 3:53

Cedric Moonen

16-Feb-07 3:53

For the second question (tox already answered the first): this is simply due to the fact that a CString class (yes, it is a class) is not compatible with whatever VB uses to represent a string.

Cédric Moonen
Software developer

Charting control [v1.1]

C^hris L^osinger16-Feb-07 3:57

16-Feb-07 3:57

sanjutvm wrote:
Why is this so?

because you've only allocated one byte for s1.

2. just guessing here... tough to say based on what you've shown us. but i doubt vb.net knows anything at all about MFCs CString class. generally, when exposing functions to be called from other languages, it's best to stick to primitive types:

BOOL _stdcall SetName(const char *pName)
{
  Myfn(pName);
}

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sanjutvm18-Feb-07 19:45

18-Feb-07 19:45

Hi All,

Thanks for the reply.
How do I perform strcpy on two char* variables?

Thanks & Regards,
sanju.

C^hris L^osinger19-Feb-07 1:16

19-Feb-07 1:16

you simply have to assure that the destination buffer is large enough to hold the source.

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sanjutvm20-Feb-07 18:58

20-Feb-07 18:58

Hi,

Thanks for the reply.

That means i cannot simply use char* as destination in strcpy. I'll have to use char* s = new char[some value].

Thanks & Regards,
sanju.

C^hris L^osinger21-Feb-07 0:58

21-Feb-07 0:58

correct. or, if you know your strings will always be smaller than a certain size, you can use something like:

char buf[MAX_SIZE];
strncpy(buf, inputString, MAX_SIZE-1)

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sanjutvm23-Feb-07 3:29

Working with huge Floating Point Numbers

23-Feb-07 3:29

Hi,

Thank you.

Thanks & Regards,
sanju.

Semion_N16-Feb-07 2:57

16-Feb-07 2:57

Hello,
I need a class which I can work with a huge floating point numbers and make an operations with them like *-/+
for example: 122354554654549878987.003253265465454597 * 65465465456654564.3212154654
I need something like this http://www.codeproject.com/cpp/largenumber.asp[^] but with floating point numbers.
Is there any class like I want?

SnaidiS(Semion)

Newbie0016-Feb-07 3:51

Newbie00

16-Feb-07 3:51

Why won't you use long double type?

C^hris L^osinger16-Feb-07 3:52

16-Feb-07 3:52

a little Googling turns up a few high-precision floating point libs for C++.

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Semion_N16-Feb-07 4:14

16-Feb-07 4:14

do you think http://savannah.nongnu.org/projects/hpalib[^]
will fulfill my requirements I mentioned?

SnaidiS(Semion)

C^hris L^osinger16-Feb-07 4:25

16-Feb-07 4:25

it says it can handle numbers in the range: 2^16384 > x > 2^[-16383]

that's far greater than the numbers you gave in your post

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Semion_N16-Feb-07 9:22

16-Feb-07 9:22

I have problems with the files.
I added the src folder to the project like that:
Tools->Options->Projects And Solutions->VC++ Directories-> and to included files and source files.
I'll show you here the most important code:

<br />
#include "stdafx.h"<br />
#include "num.h"<br />
#include "numDlg.h"<br />
#include "stdio.h"<br />
#include "xpre.h"<br />
<br />
<br />
BOOL CnumDlg::OnInitDialog()<br />
{<br />
	CDialog::OnInitDialog();<br />
        <br />
        CnumDlg::play();<br />
<br />
   <br />
	return TRUE;  // return TRUE  unless you set the focus to a control<br />
}<br />
<br />
<br />
void CnumDlg::play()<br />
{<br />
 struct xpr s;<br />
    int i,n;<br />
	<br />
    s=xZero;<br />
    do<br />
    {<br />
        scanf("%d",&n);<br />
        s=xZero;<br />
        for(i=0;i<=n;i++)<br />
            s=xadd(s,xpr2(xOne,i),0);<br />
        xprxpr(s,30);<br />
        putchar('\n');<br />
    }while (n>0);<br />
}<br />

I earased the most of the code-just the important there.
After I'm running the program I have the following Errors:

1>numDlg.obj : error LNK2019: unresolved external symbol _xprxpr referenced in function "public: void __thiscall CnumDlg::play(void)" (?play@CnumDlg@@QAEXXZ)<br />
1>numDlg.obj : error LNK2019: unresolved external symbol _xadd referenced in function "public: void __thiscall CnumDlg::play(void)" (?play@CnumDlg@@QAEXXZ)<br />
1>numDlg.obj : error LNK2019: unresolved external symbol _xpr2 referenced in function "public: void __thiscall CnumDlg::play(void)" (?play@CnumDlg@@QAEXXZ)<br />
1>numDlg.obj : error LNK2001: unresolved external symbol _xOne<br />
1>numDlg.obj : error LNK2001: unresolved external symbol _xZero<br />
1>C:\Documents and Settings\Semion Naidis\My Documents\Visual Studio 2005\Projects\num\Debug\num.exe : fatal error LNK1120: 5 unresolved externals

How can I fix that?

SnaidiS(Semion)

C^hris L^osinger16-Feb-07 10:09

16-Feb-07 10:09

you'll need to either provide definitions for those functions, or remove the calls to them.

Semion_N16-Feb-07 18:46