Re: FormatMessage LoadString from string table

From:
mfc <mfcprog@googlemail.com>
Newsgroups:
microsoft.public.vc.mfc
Date:
Tue, 14 Sep 2010 12:15:22 -0700 (PDT)
Message-ID:
<418d4abc-2930-47f8-be94-aabf1cad798c@u13g2000vbo.googlegroups.com>
On 14 Sep., 20:26, Joseph M. Newcomer <newco...@flounder.com> wrote:

See below...

On Tue, 14 Sep 2010 09:41:38 -0700 (PDT), mfc <mfcp...@googlemail.com> wr=

ote:

Why write a function, when you could have written instead a simple + o=

perator on the

CString values?


I`ve two CStrings which looks like

CString str3items ("here should be the first item %1, here should be
the second item %2, here should be the third item %3 and so on");
CString str2items ("here should be the first item %1, here should be
the second item %2);

CString firstItem ("first");
CString secondItem ("second");
CString thirdItem ("third");

Now I want to use FormatMessage to add these items to str2items or
str3items;


*
If you wish to be able to re-order the sequences of items using %n, then,=

 indeed, you are

going to need some number of %i values. So make this formatting string=

 the first string

in the sequence: IDS_TEST_FIRST. Start your loop at IDS_TEST_FIRST+1. =

 Then your

formatting string and the strings it handles are all in the resource STRI=

NGTABLE and easy

to maintain!

Or, if it is some kind of XML template, then it might say

<%1:%2 value="%3"
    <%1:%4 name="%5"....

and so on, which is how I create the templates for my Locale Explorer. =

 I allow the user

to specify template files. Again, this is not Rocket Science, just usi=

ng the obvious

mechanisms in the obvious way. And if you need to have an array of 40 =

strings, well,

that's just tough, because what you want to do REQUIRES an array of 40 st=

rings (or 42, or

47, or 51, so if if you hardwire this value you have made a very deep and=

 fundamental

programming error)

CString DoSubstitution(const CString & template)
     {
      CStringArray Parameters;
      for(int i = IDS_START; i < IDS_MAX; i++)
         { /* data loop */
          CString s;
          s.LoadString(IDS_START+i);
          if(s.IsEmpty())
                 break;
          Parameters.Add(s);
         } /* data loop */
        LPTSTR msg;
      ::FormatMessage(FORMAT_MESSAGE_ALLOCATE_BUFFER | FORMAT_MESSA=

GE_FROM_STRING,

                                    =

   ...provide various parmeters (Exercise for the

Reader )
                                    =

   (LPTSTR)&msg,

                       ....more parameters
                                    =

   Parameters.GetSize(),

                                    =

   Parameters.GetData());

          CString result(msg);
          LocalFree(msg);
          return result;
       }

Error checking is left as an Exercise for the Reader. I think the last=

 two parameters are

the string count and the string array pointer, but this is an EFTR.

Note that at NO POINT does this code presume there is a fixed number of s=

trings, just a

maximum upper bound (e.g., 100, whereas I might only be using 27 of those=

 strings)

My string table normally looks like
IDS_TEST <...This is the start of the sequence of strings used for...>
IDS_MAX <..All strings must fit in this range>

Note I set IDS_MAX to be IDS_TEST+100, e.g., I define IDS_TEST=10000 an=

d set IDS_MAX to be

10100, and start my loop at IDS_TEST+1, so I have actual DOCUMENTATION in=

 my string table.

NEVER assume that because MFC doesn't have some capability you need that =

is possessed by

the raw API that you cannot use the raw API! Just use it!

Take a look at my FormatMessage example, or look at the numerous calls on=

 FormatMessage in

my Locale Explorer source.
                                    =

    joe

*****


thanks for your help. The part with the CStringArray is totally clear
to me but the FormatMessage() call is not clear to me...

Only a small demo code;

LPTSTR msg ("%1% and %2% and %3%"); //represents the string which
should include all itmes from the CStringArray after the
FormatMessage()-call -> see out-string

LPWSTR out = NULL; //output-string which includes the msg-string
with all arguments from the CStringArray

::FormatMessage(FORMAT_MESSAGE_ALLOCATE_BUFFER |
FORMAT_MESSAGE_FROM_STRING,
                           (LPTSTR)&msg, //lpSource (in - Pointer to a
string that consists of unformatted message text)
                           0,
                           0,
                          (LPWSTR ) &out, //lpBuffer(out A pointer to
a buffer that receives the null-terminated string that specifies the
formatted message)
                          0,
                          (va_list *)0
};

the (va_list*) argument seems to me that it should include the
Parameter.GetData() CStringArray - but that doesn`t work...

va_list args = NULL;
va_start(args, Parameters.GetData());

also (va_list *)Parameters.GetData() in the function call
FormatMessage() won`t work.

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