C / C++ / MFC

7-May-12 10:34

This is my first time using try and catch in c++. I know how to use it in vb, but not sure in c++. I would like to capture the error message or code, and do something, but I'm not what to put there, and the format required so it works.

I did google this, but all I could find was char str.

try {
     // test and see if we can write to the AppHostWritableAdminManager
     hr = CoCreateInstance( __uuidof(AppHostWritableAdminManager), NULL,
     CLSCTX_INPROC_SERVER, __uuidof(IAppHostWritableAdminManager), (void**) &pMgr);
    }
    catch ( char str ) {
        goto CLEANUP;
    }

Chuck O'Toole7-May-12 10:45

7-May-12 10:45

try this

catch (CDBException *e)
{
    AfxMessageBox("Caught Error: " + e->m_strError);
    // do something like "close" a file / database or whatever corrective action
}

or use CException *e instead of the Database class variant.

In other words, you have to "catch" what something else "throws" and that depends on what routines you are calling that could throw an exception.

jkirkerx7-May-12 10:50

7-May-12 10:50

Thanks Chuck

Is it different for just straight win32?

CDBException

[EDIT]

Nevermind, it's just like vb, I just need to find the correct value for comm.

Chuck O'Toole7-May-12 12:13

7-May-12 12:13

I don't do a lot of non-MFC these days because I find the classes so useful. It's also hard to show something useful without it containing a lot of stuff that's specific to my application and would make no sense to you. CDBException is for errors coming from CDatabase and CRecordset classes.

Here's my general exception catcher in the main loop of my application. Ignore things that are related to sending messages back to the user (client / server app).

C++

catch (CException * cfe)
   {
	char exceptBuf[255];
	CString ts;
	CString ccnum;
	
	if (!cfe->GetErrorMessage(exceptBuf, sizeof(exceptBuf)))
		exceptBuf[0] = '\0';		/* null out the message if no text associated with exception */
#ifdef _DEBUG
	AfxMessageBox(exceptBuf);
#endif
	if (claim_check != NULL)
		ccnum = claim_check->getClaimCheck();
	else
		ccnum = "000000";
	ts.Format("Internal Exception Trap - %s", exceptBuf);
	TheLogFile->LogThis(ccnum + CString(" : ") + ts);
	sendErrorToGUI(ts, E_DEFAULTERROR, TheCommCenter, claim_check, parsed_request, inputConfig);
   } /* catch block */

jkirkerx7-May-12 12:58

7-May-12 12:58

The first post was very helpful, I realized it was the same as vb, and I had to find the right exception, in which my case was exception literally.

I can't reproduce the error so I can test catch it, but I did the messagebox which is good enough for now. I don't expect it to ever trigger the catch anymore, since fixing all my errors.

Thanks Chunk

Aescleal8-May-12 3:55

Aescleal

8-May-12 3:55

Unfortunately CoCreateInstance isn't a C++ function so it won't throw exceptions - unless someone's implemented a wrapper or something around the function that we can't see in your example.

For COM and OLE functions you have to pull apart the HRESULT return value, preferably using the Microsoft macros and/or call GetLastError/FormatMessage. It's a pain in the bum but COM and OLE are pretty old now and MS haven't quite managed to kill it off or hide it yet.

What the various return values mean can be found here[^].

Edit for English fail.

jkirkerx8-May-12 6:55

Can not Find Functions In Static Library

8-May-12 6:55

I didn't know it was old school, and thought it was the current way to talk to IIS 7+ web server.

It must of stopped due to one of the previous errors I made earlier. So I will use the hr check instead.

Thanks for the heads up on that.

// test and see if we can write to the AppHostWritableAdminManager
hr = CoCreateInstance( __uuidof( AppHostWritableAdminManager ), NULL,
			CLSCTX_INPROC_SERVER, __uuidof( IAppHostWritableAdminManager ), (void**) &pMgr);
if ( FAILED( hr ) )
	goto CLEANUP;

AmbiguousName7-May-12 1:37

7-May-12 1:37

hello guys... This error has something to do with linking. I have a static library (which contains some virtual functions) and I have taken following steps to add it to my project.

- Project Name -> Add -> Existing Item . Chose and included header file.

- Project Name -> Properties -> C/C++ -> General -> Additional Include Directories. Navigated to the folder containing the header file.

- Project Name -> Properties -> Linker -> Input -> Additional Dependencies . Gave the path including the library_name.lib

Until here, it compiles successfully. But when I derive a class from a class in this header file, it starts giving this error like: Error LNK 2001 - Unresolved External Symbols? Whats wrong with this approach? Thanks for any input.

This world is going to explode due to international politics, SOON.

modified 7-May-12 8:54am.

Chris Meech7-May-12 4:10

Chris Meech

7-May-12 4:10

I'm not sure, but the specification of Additional Dependencies may only affect the bulding and re-building of your project. I think you have to specify additional linker directories to use and also additional libraries to include. This are usually in the same place or tab as the Additional Dependencies. Smile | :)

Chris Meech
I am Canadian. [heard in a local bar]

In theory there is no difference between theory and practice. In practice there is. [Yogi Berra]

posting about Crystal Reports here is like discussing gay marriage on a catholic church’s website.[Nishant Sivakumar]

Albert Holguin7-May-12 7:33

Albert Holguin

7-May-12 7:33

This looks like it should work... in the header that you have included, make sure you don't have to #define anything to specify that you are using the library instead of building it. Sometimes developers use the same exact header file to build the library than what others would use to import the library and just use pre-processor directives to tell the difference.

What are the external symbols that it can't find? Are they defined in the header?

AmbiguousName7-May-12 7:42

7-May-12 7:42

Albert Holguin wrote:
What are the external symbols that it can't find? Are they defined in the header?

Yes. They are virtual functions and are defined in the header file.

This world is going to explode due to international politics, SOON.

Chuck O'Toole7-May-12 8:09

7-May-12 8:09

Regular "virtual" or "pure virtual"? Makes a difference. Please post the definition from the header file so we can see.

AmbiguousName7-May-12 18:47

7-May-12 18:47

Well they are regular virtual functions. An example of them can be like this

C++

virtual void OnAdd(double n1, double n2);
virtual void OnSub(double n1, double n2);
virtual void OnMul(double n1, double n2);
virtual void OnMul(double n1, double n2);

Now I have implemented a similar application whose architecture is exactly same. Four arithmetic virtual functions in a library which I later included in the project. Then I derived a class from this lib's class and overrided those functions. It worked successfully.

This world is going to explode due to international politics, SOON.

Chuck O'Toole7-May-12 19:41

7-May-12 19:41

I hate to ask a question that should have been asked first. What is the exact error message. Which "symbol" is unresolved, the one in the base class or the one in your derived class? If it's the former, then the problem is that your library is not included in the linker section as an additional library. If it's the latter, then the problem is in your code and the definition of the overridden members.

AmbiguousName7-May-12 20:10

7-May-12 20:10

That's in base class. But it is solved by strange method. What I did is:
- I overrided all the virtual functions in the the derived class (although left function bodies blank Smile | :)

).

This solved my problem. But I am thinking why it should have been a problem. I mean usually virtual functions are meant to be overriden, what if I don't want to override them at a particular point.

Well it is becoming messy, I am happy that my problem is solved for now.

This world is going to explode due to international politics, SOON.

Chuck O'Toole8-May-12 3:46

8-May-12 3:46

You didn't "solve" the problem, you only made the "symptoms" go away. Now you have empty functions overriding ones that may have done something useful, as you've discovered.

If it can't find the functions in the library then:

1) you didn't list the library as an input to the linker (both debug and release)
2) you are feeding in the wrong library
3) they are not in the library

You need to go back to the person / source that gave you the library and ask them about the contents and why you are having this particular problem. I'm going to stop offering suggestions on this one.

AmbiguousName8-May-12 9:06

CRichEditCtrl interface question

8-May-12 9:06

As I stated earlier, I made a similar application (calculator) with exactly same architecture and it worked. Well I did ask him. But that poor guy could not answer me. He could only give a possible solution that was: may be its due to the character set.
- The library was made using: Not Set.
- While my solution was made using: Use Unicode Character set.
But he was not sure what the problem could be. Anyway, thank you very much for your time.

This world is going to explode due to international politics, SOON.

ForNow6-May-12 6:32

ForNow

6-May-12 6:32

Hi,

As some of you may already be aware from some of my post I am a MainFrame Assembler programmer trying to get into the Windows MFC platform

This presented me with a number of challanges to name two

1) Understanding Object Oriented as opposed to procedural coding

2) thinking of text as fonts instead of bytes oriented characters

Well it seems that RichEdit interface deals with characters e.g ( SetSel API) instead

of fonts

So Here is my problem listed below is the text I am displaying in a RichEdit window

  000000                00000 004A4    10 TESTA CSECT
                                      11 TESTA AMODE 31
                                      12 TESTA RMODE ANY
                                      13         YREGS
0                      00000          15+R0       EQU   0                                                        01-YREGS
                       00001          16+R1       EQU   1                                                        01-YREGS
                       00002          17+R2       EQU   2                                                        01-YREGS
                       00003          18+R3       EQU   3                                                        01-YREGS
                       00004          19+R4       EQU   4                                                        01-YREGS
                       00005          20+R5       EQU   5                                                        01-YREGS
                       00006          21+R6       EQU   6                                                        01-YREGS
                       00007          22+R7       EQU   7                                                        01-YREGS
                       00008          23+R8       EQU   8                                                        01-YREGS
                       00009          24+R9       EQU   9                                                        01-YREGS
                       0000A          25+R10      EQU   10                                                       01-YREGS
                       0000B          26+R11      EQU   11                                                       01-YREGS
                       0000C          27+R12      EQU   12                                                       01-YREGS
                       0000D          28+R13      EQU   13                                                       01-YREGS
                       0000E          29+R14      EQU   14                                                       01-YREGS
                       0000F          30+R15      EQU   15                                                       01-YREGS
0                      00007          32 XLNK    EQU    R7
 _ 000000                               33 ARNDCOPY DS    0H
 _ 000000 90EC D00C            0000C    34         STM    R14,R12,12(R13)
 _ 000004 18CF                          35         LR     R12,R15
                  R:C  00000          36         USING  TESTA,R12
                                      37 *       HERCDIE LINKAGE=SVC
_ 000006 18ED                          38         LR     R14,R13
_ 000008 41D0 C314            00314    39         LA     R13,SAVEAREA
_ 00000C 50E0 C318            00318    40         ST     R14,SAVEAREA+4
_ 000010 50C0 C38C            0038C    41          ST    R12,WORKFLD
_ 000014 F384 C391 C38C 00391 0038C    42          UNPK  WORFLD1,WORKFLD(5)
_ 00001A DC08 C391 C39A 00391 0039A    43          TR    WORFLD1,TR_TBL
                                      44          LOAD  EP=TESTB
_ 000020                               46+         CNOP  0,4                                             @YA29363 01-LOAD
_ 000020 4DF0 C02C            0002C    47+         BAS   15,LOAD2_0002      BRANCH AROUND CONSTANT(S)             01-LOAD
 000024                               48+LD2_0002    DS 0H                                                       01-LOAD
 000024 E3C5E2E3C2404040              49+LE2_0002    DC CL8'TESTB'         ENTRY POINT NAME                      01-LOAD
 00002C                               50+LOAD2_0002    DS 0H                                                     01-LOAD
_ 00002C 4100 F000            00000    51+         LA    0,LE2_0002-LD2_0002(,15)         ADDR OF PARAMETER       01-LOAD
_ 000030 1B11                          52+         SR    1,1                SHOW NO DCB PRESENT                   01-LOAD
_ 000032 0A08                          53+         SVC   8                                                        01-LOAD
_ 000034 D207 C37B C391 0037B 00391    54          MVC   STARTS,WORFLD1
                                      55 *        WTOR  TEXT=(START_ADDR,REPLY,1,ECB_REPLY)
                                      56 *        WAIT  ECB=ECB_REPLY
1                                                                                                               Page    4

C++

I am trying to highlight the first Mainframe executable line which is the line with 
the following text    STM  R14,R12,12(R13)

Here is the code I use to that 
	// LOOK for the irst executable instruction 
SetSel(0,0);         // start at the beginig

FINDTEXTEX ft;
ft.chrg.cpMin = 0;
ft.chrg.cpMax = -1;
ft.lpstrText = (LPSTR) "_ ";

long n = FindText(FR_DOWN|FR_MATCHCASE | FR_WHOLEWORD, &ft);

long l = LineLength(n);

From my understanding all return codes from the richedit api 0 character based
however When step thru the code of the FindText api the return code is some huge number X'830' decimal 2096 this what is in the AX register which typically is where the return code is

It seems obvious to me that the first under score is about 150 characters away ( I didn't do a exact count ) but it is in that range

Anyway if someone could explain I would apprecaite it

enhzflep6-May-12 7:21

enhzflep

6-May-12 7:21

Howdy again, I just cut and past the asm listing into notepad++ to find the location of the first "_ " - in my case it was character 2258 - 0x8D2.

Don't know where the extra 162 extra bytes come from, though they seem likely to be unimportant to the discussion at this point.

Hey, what sort of machine is that ASM for? I'm curious, not recognizing the opcodes as belonging to any of the variants I've coded for.

Re: CRichEditCtrl interface question [modified]

ForNow6-May-12 9:07

ForNow

6-May-12 9:07

MainFrame Assembler as I said I am MainFrame Assembler programmer

So if the the first "_ " is 2258 from the Richeditctrl

then the following code should color the line with the STM red

C++

CHARFORMAT cfm;

long n = FindText(FR_DOWN|FR_MATCHCASE | FR_WHOLEWORD, &ft);

long l = LineLength(n);

   SetSel(n,l);

    cfm.cbSize = sizeof(CHARFORMAT);
    cf.dwMask = CFM_COLOR;
    cf.crTextColor  = RGB(255,0,0);

      SetDefaultCharFormat(cfm);

enhzflep6-May-12 10:14

enhzflep

6-May-12 10:14

Indeed. I was actually thinking more along the lines of what sort of mainframe? e.g US Military, CRAY, and a couple of other whose name escapes me just now. I played with DEC Alphas a million years ago, MIPS before the orig PlayStation implemented it, Had a couple of old SuperSparc's sitting in cases in the CS building in uni. Perhaps I was simply too inarticulate. No matter. Sorry for my intrusiveness. Blush | :O

Yeah, one would certainly think that your code would colour the line red - though I've been spectacularly unsuccessful at changing the text colour using MFC. I can make the line bold, underlined or whatever - but I can't color the text. The same task I have easily achieved in native code in the past and cant see any special colour handling functions that seem relevant. I'm more than a little perplexed just now. Here's the (hacked together)code I have for Bolding the target line.

Also, for some reason I had to remove the other flags you'd used in FindText. It wouldn't return a valid hit for the text "_ " unless I did so, too tired to read help docs just at the moment, no doubt such limitations are mentioned in there somewhere.

~~Of course, if you change the "or equals" to "xor equals" you can toggle the state, rather than just setting it.~~
Oops! I mean, if you xor the dwEffects with CF_BOLD, instead of setting it - you'll toggle the state of the char formatting.

Also, you should be using SetSelectionCharFormat, SetDefaultCharFormat acts on the whole control, not just the selection.

C++

void CmfcRichEditDlg::OnBnClickedButton3()
{
    // TODO: Add your control notification handler code here
    FINDTEXTEX ft;
    CHARFORMAT cfm;

    ft.chrg.cpMin = 0;
    ft.chrg.cpMax = -1;
    ft.lpstrText = "_ ";

    long n = m_RichEdit.FindText(FR_DOWN, &amp;ft);
    long l = m_RichEdit.LineLength(n);

    m_RichEdit.SetSel(n,l);

    m_RichEdit.GetSelectionCharFormat(cfm);

    cfm.dwMask |= CFM_BOLD;
    cfm.dwEffects = CFE_BOLD;

    m_RichEdit.SetSelectionCharFormat(cfm);
}

modified 6-May-12 16:32pm.

enhzflep6-May-12 11:01

enhzflep

6-May-12 11:01

Thought I'd add another reply so that you get a notification.

Just solved the question of why no colouring?

I tried it as a release-mode app and voila! Tried again as a debug, Nada!

Anyways, here's a function that will flip the line back and forth between
std-weight black text & bold red text.

C++

void CmfcRichEditDlg::OnBnClickedButton3()
{
	// TODO: Add your control notification handler code here
	FINDTEXTEX ft;
	CHARFORMAT cfm;
	
	ft.chrg.cpMin = 0;
	ft.chrg.cpMax = -1;
	ft.lpstrText = "_ ";

	long n = m_RichEdit.FindText(FR_DOWN, &ft);
	long l = m_RichEdit.LineLength(n);

	m_RichEdit.SetSel(n,l);

	m_RichEdit.GetSelectionCharFormat(cfm);
	cfm.cbSize = sizeof(cfm);
	cfm.dwMask = CFM_BOLD;
	cfm.dwEffects ^= CFE_BOLD;
 	m_RichEdit.SetSelectionCharFormat(cfm);


	cfm.cbSize = sizeof(cfm);
	if (cfm.crTextColor == RGB(0,0,0))
		cfm.crTextColor = RGB(200,0,0);
	else
		cfm.crTextColor = RGB(0,0,0);

	cfm.dwMask = CFM_COLOR;
	cfm.dwEffects = NULL;
	m_RichEdit.SetSelectionCharFormat(cfm);
}