ATL / WTL / STL

Re: Here is a C Program showing some Error, Give some solution

10-Jun-13 6:03

Please format the code block properly, and identify line 33.

Use the best guess

Krishnakumartg13-Aug-13 7:05

Krishnakumartg

13-Aug-13 7:05

Replace

int *val1,*val2;
int *oper;
 
void calc(val1,val2,oper)

with

//int *val1,*val2;
//int *oper;

void calc(int* val1,int* val2,int* oper)

std::map and error checking

bkelly139-Jun-13 10:42

9-Jun-13 10:42

Windows 7, Visual Studio 2008, MFC, C++, Dialog

My application makes use of an std::map, inserting records with the following:

m_tmats_definition_map[ the_key ] =  m_one_definition_record;

the_key is a CString and m_one_definition_record is a structure of several CStrings and a few various fields such as integers.

That seems to be working. Now in the event something does not work out right I want some error checking. I am not finding much of anything concerning run time checking on this insert operation. Probably not looking in the right places or using the right search phrase. Where can I look to find a good discussion on this topic?

Thanks for your time
If you work with telemetry, please check this bulletin board: http://www.bkelly.ws/irig_106/

Garth J Lancaster9-Jun-13 13:18

Garth J Lancaster

9-Jun-13 13:18

ouch - hard question - I just had a look and its a right PITA - 'Dinkumware' and SGI used to have good manuals (and even finding what exceptions are thrown within is hard enough)

SGI's manual page for MAP is ... http://www.sgi.com/tech/stl/Map.html[^]

that may give you a start point - what sort of error's do you expect ? dont forget that map doesnt throw an error for a duplicate key value (the commonest issue I guess) - it simply replaces the existing value... for that reason, you should use find() first on the map to see if the value already exists

'g'

bkelly139-Jun-13 14:16

9-Jun-13 14:16

I don't know what sort of errors to expect. Isn't that one of the joys of software? <grin>
Good link.
Good point with the Find(). I do want to know if there are duplicates and will incorporate that.

Thanks for your time
If you work with telemetry, please check this bulletin board: http://www.bkelly.ws/irig_106/

Richard MacCutchan9-Jun-13 21:23

9-Jun-13 21:23

You need to check return values of function calls that provide information. See here[^] for the insert function.

Use the best guess

status display in a dialog

MicroVirus11-Jun-13 12:07

MicroVirus

11-Jun-13 12:07

In this case, there's nothing you need to do. If something goes wrong, it'll throw a C++ exception. Most likely causes will be that a new element can't be constructed, or that there is insufficient memory.
But maybe this is not what you meant. You say you want error checking; why do you want error checking? What is that you want to accomplish? Perhaps the solution is different.

bkelly139-Jun-13 5:17

Re: status display in a dialog

9-Jun-13 5:17

Windows 7, Visual Studio MFC, C++, dialog based project

A dialog is to have a status display area. The code will add lines of text. My preference is for each new line of text to be added to the bottom and have the display scroll up. The user will not be able to edit the text, but it would be nice to be able to capture it with ctl-c to paste somewhere else.

I tried an edit control but each update wipes out the previous text.
List box seems to be the simplest control, yet still has many user accessible features.

I would like to read your reccomendations.

Thanks for your time
If you work with telemetry, please check this bulletin board: http://www.bkelly.ws/irig_106/

Garth J Lancaster9-Jun-13 14:53

Garth J Lancaster

9-Jun-13 14:53

have a look at this - its what I used for years when I did MFC

A Logging Listbox Control[^]

[edit] I can probably remember how to use it in a Dialog based app if you think you want to use it
Joseph's site is http://www.flounder.com/logctl.htm[^] [/edit]

'g'

std::map, fundamental get started problem RESOLVED

bkelly139-Jun-13 4:04

Re: std::map, fundamental get started problem

9-Jun-13 4:04

Windows 7, Visual Studio 2008, MFC, CPP, std::map
I am trying to get an std::map working. I have tried several permutations and patterned it after some tutorials found with a search. Still I am unable to get it right and to decipher the error message.
Please assist with this problem.
The setup

XML

typedef struct
{
   unsigned int   identifier_location;
   unsigned int   count_found;
   CString        key;
   CString        token[ MAX_TOKEN_COUNT ];
}     td_tmats_attributes_definitions;

td_tmats_attributes_definitions    m_one_definition_record;

std::map < CString, td_tmats_attributes_definitions > m_tmats_definition_map;
//          ^ the key    ^the data to store
// below is an alternate declaration.
std::map < string, td_tmats_attributes_definitions > m_tmats_definition_map_string;

And now the code

CString  the_key;
…
The code:
// The primary insertion code
 m_tmats_definition_map.insert( the_key, m_one_definition_record );
// the alternate
string str_key = the_key;
//            m_tmats_definition_map_string.insert( the_key, m_one_definition_record );

Neither of the two options will compile.

I was prepared to post the error message, but I have a strong suspicion that reader will know my error with little effort and the long text from VS output box will only clutter things up. Let me know if you want to see the error text.

Please tell me what I need to change.

Thanks for your time
If you work with telemetry, please check this bulletin board: http://www.bkelly.ws/irig_106/

modified 9-Jun-13 12:44pm.

pasztorpisti9-Jun-13 4:19

pasztorpisti

9-Jun-13 4:19

C++

m_tmats_definition_map.insert( std::make_pair(the_key, m_one_definition_record) );

C++

m_tmats_definition_map[the_key] = m_one_definition_record;

std::make_pair should be in the <utility> include.

Re: std::map, fundamental get started problem RESOLVED

bkelly139-Jun-13 4:46

CFileException, discover reasons RESOLVED

9-Jun-13 4:46

As you already know, that compiles. I see the second option as being a bit more clear and used it.
Thank you for your time.

Thanks for your time
If you work with telemetry, please check this bulletin board: http://www.bkelly.ws/irig_106/

bkelly138-Jun-13 10:05

8-Jun-13 10:05

Windows 7, 64 bit, Visual Studio 2008, MFC, C++

After a long series of searches looking for a nice method of reading from a text file into CString I arrived at the following:

<br />
CStdioFile definition_file;<br />
try<br />
      {<br />
         definition_file.Open( m_definition_file_name, CFile::modeRead );<br />
      }<br />
      catch( CFileException e )<br />
      {<br />
         e.m_cause;<br />
      }<br />

This is from the VS help utility:

<br />
catch( CFileException* e )<br />
{<br />
   if( e->m_cause == CFileException::fileNotFound )<br />
      printf( "ERROR: File not found\n")<br />
   e->Delete();<br />
}<br />

This leads to the concept

<br />
if( e->m_cause == CFileException::fileNotFound )<br />
      printf( "ERROR: File not found\n");<br />
elseif( e->m_cause == CFileException::generic )<br />
      printf( "ERROR: An unspecified error occurred.\n");<br />
elseif  etc etc<br />

Is there a better way of capturing the text of the error rather than an if/else/else/else sequence?
Note: I am open to any type of suggestion. The goal is to read a CSV text file and parse it into a std::map.

Thanks for your time
If you work with telemetry, please check this bulletin board: http://www.bkelly.ws/irig_106/

Richard MacCutchan8-Jun-13 21:40

Re: CFileException, discover reasons RESOLVED

8-Jun-13 21:40

Use the GetErrorMessage[^] member function.

Use the best guess

bkelly139-Jun-13 3:54

9-Jun-13 3:54

Cool.
Thank you.

Thanks for your time
If you work with telemetry, please check this bulletin board: http://www.bkelly.ws/irig_106/

bkelly139-Jun-13 6:11

9-Jun-13 6:11

Oops, I have a follow up on this.
Declarations:

CSS

CFileException     get_error_message;
 const unsigned int ERROR_MAX = 64;
 char  char_error_text[ ERROR_MAX ];
 LPTSTR ptr_error_text = &char_error_text[0];
 CString final_error_message = "";

Code:

m_definition_file_name += "x";
try
{
   m_definition_file.Open( m_definition_file_name, CFile::modeRead );
   get_error_message.GetErrorMessage( ptr_error_text, ERROR_MAX, NULL );
   final_error_message = char_error_text;
   error_number = GetLastError();

}
catch( CFileException e )
{ code }
catch( ... )
{ code }
{

The line m_definition_file_name += "x" forces the file name to be incorrect.

Char array char_error_text winds up with "No error occurred." while error_number gets 0 (zero)
When the line error_number = GetLastErrror is moved directly beneath the open command, it get the value 2 (two). But that consumes the last error and get_error_message does not get anything.
Nothing is thrown and neither catch is activated.

What do I need to change to use this CFileException?

Thanks for your time
If you work with telemetry, please check this bulletin board: http://www.bkelly.ws/irig_106/

Richard MacCutchan9-Jun-13 9:23

9-Jun-13 9:23

I don't understand what you are doing here; it should be:

C++

try
{
   // code to open the CFile
}
catch (CFileException ce)
{
    TCHAR message[132];
    if (ce.GetErrorMessage(message, 132, NULL)
    {
        // display the contents of the message buffer
    }
}

Use the best guess

bkelly139-Jun-13 9:43

9-Jun-13 9:43

Hello,
I don't see what you have different. Second, when the file does not exist, this Open method does not throw an exception, so none of the try/catch matters. I had a catch(...) at the bottom and it was not entered.

Thanks for your time
If you work with telemetry, please check this bulletin board: http://www.bkelly.ws/irig_106/

Richard MacCutchan9-Jun-13 20:41

9-Jun-13 20:41

If the open function does not throw an error then you need to check the return value and call GetLastError() to find out why, as described here[^]. Alternatively you can throw a new exception like:

C++

try
{
   if (!m_definition_file.Open(m_definition_file_name, CFile::modeRead))
   {
       DWORD error_number = GetLastError();
       throw new CFileException::OsErrorToException(error_number);
   }
}
catch( CFileException e )
{
    // handle the exception
}

Note that when calling GetLastError() you must call it immediately after the failing API function call, otherwise its return may not be valid.

Use the best guess

tried FormatMessage()

bkelly139-Jun-13 7:07

Still looking for reason text

9-Jun-13 7:07

I have also tried this.
Declarations:

CSS

const unsigned int ERROR_MAX = 64;
char  char_error_text[ ERROR_MAX ];
LPTSTR ptr_error_text = &char_error_text[0];
CString final_error_message = "";

With this code

m_definition_file.Open( m_definition_file_name, CFile::modeRead );
error_number = GetLastError();
format_message_return = FormatMessage(  0,              // dwFlags
                                        NULL,           // lpSousrce
                                        error_number,   // dwMessageID
                                        NULL,           // dwLanguageId
                                        ptr_error_text, // lpBuffer
                                        ERROR_MAX,      // nSize
                                        NULL     );     // Arguments
final_error_message = char_error_text;

The error number is 2 (two). char_error_text ends up with nothing. I am uncertain of the arguments for FormatMessage. The file name is forced to be incorrect and an error is expected.

Thanks for your time
If you work with telemetry, please check this bulletin board: http://www.bkelly.ws/irig_106/

bkelly1322-Jun-13 12:17

Re: Still looking for reason text

22-Jun-13 12:17

I have yet to get a text based error code for opening a file. Here is the simplified code:

C++

m_definition_file_name = Select_Definition_File.GetPathName();
m_definition_file_name += "x";  // make the file name bad
m_definition_file.Open( m_definition_file_name, CFile::modeRead );

//  error_number = GetLastError();  // restore to verify error code is 2
get_error_message.GetErrorMessage( ptr_error_text, ERROR_MAX, NULL );
final_error_message = char_error_text;  // says no error

The Open method does not throw an exception. When GetLasError() is used, the error code is 2 (two).
The GetErrorMesssage yields No error returned, which is incorrect. The file could not be opened because it does not exist.

GetErrorMessage(...) is has three arguments about formatting the error message, but the error message is not an argument. I presume it gets the error message like GetLastError() does, but this appears incorrect.

How do I get a text string describing this error?

Thanks for your time
If you work with telemetry, please check this bulletin board: http://www.bkelly.ws/irig_106/

Richard MacCutchan23-Jun-13 0:51

Re: Still looking for reason text

23-Jun-13 0:51

I gave you a suggested solution at http://www.codeproject.com/Messages/4583835/Re-CFileException-discover-reasons.aspx[^], which should throw an exception whose value would be CFileException::fileNotFound (error code 2). Did you try it, and if so what result did you get?

In response to your comment about FormatMessage, you need to tell the function where to look for the mappings of error codes to messages thus:

C++

format_message_return = FormatMessage(FORMAT_MESSAGE_FROM_SYSTEM,  // dwFlags
                                        NULL,           // lpSousrce
                                        error_number,   // dwMessageID
                                        NULL,           // dwLanguageId
                                        ptr_error_text, // lpBuffer
                                        ERROR_MAX,      // nSize
                                        NULL     );     // Arguments

This is explained in full detail in the documentation[^].

Use the best guess

bkelly134-Jul-13 11:05

Re: Still looking for reason text

4-Jul-13 11:05

My apologies for no replying sooner. I followed your advice and now have that FormatMessage method working. Thank you.

Thanks for your time
If you work with telemetry, please check this bulletin board: http://www.bkelly.ws/irig_106/

Richard MacCutchan4-Jul-13 20:50