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  4. Std::string loadstring???

Std::string loadstring???

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  • L Lost User

    Hi, Not sure who gave me a one vote... but the solution I presented is a secure and safe method for loading a std::string from a resource. The method presented by Aescleal will fail for a string greater than the 4096 constant. The wstring solution presented by Stephen Hewitt just flat out doesn't work for std::string Best Wishes, -David Delaune

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    Stephen Hewitt
    wrote on last edited by
    #10

    It does for a wstring (which was all it was intended to, it wasn't a reply to the OP but to Aescleal). It's documented. MSDN (on LoadString):

    nBufferMax [in] int The size of the buffer, in characters. The string is truncated and null-terminated if it is longer than the number of characters specified. If this parameter is 0, then lpBuffer receives a read-only pointer to the resource itself.

    Secondly, I tried it (after reading the documentation thoroughly first) and verified that it did work. Finally, your technique will not work. LoadResource returns nothing that LoadString can consume.

    Steve

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    • S Stephen Hewitt

      I'm not positive, but it doesn't seem to. Note that the documentation says it returns a pointer to the raw resource and string resources are always Unicode, so perhaps this is a reason. In fact, in the ANSI case 0xFFFFffff was returned to indicate an error (when 0 is passed as the buffer size), which isn't mentioned in the documentation.

      Steve

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      Aescleal
      wrote on last edited by
      #11

      Thanks for that, I'll stick that on the list as the first new thing I've learnt today. Ash

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      • L Lost User

        Hi, Not sure who gave me a one vote... but the solution I presented is a secure and safe method for loading a std::string from a resource. The method presented by Aescleal will fail for a string greater than the 4096 constant. The wstring solution presented by Stephen Hewitt just flat out doesn't work for std::string Best Wishes, -David Delaune

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        Aescleal
        wrote on last edited by
        #12

        I didn't give you a 1 vote but the method I outlined will work for strings greater than 4096 characters, it just won't load the whole string. If you're really worried about that you have to use the OS/2 vintage "try it once to fail, once to succeed" method of sizing buffers. And it'd be fairly easy to change Stephen's method to work for std::string - depending on how much you know about the resource and the characters in it it's either trivial (use the two iterator string constructor) or slightly harder (use wcstombs). Ash

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        • S Stephen Hewitt

          It does for a wstring (which was all it was intended to, it wasn't a reply to the OP but to Aescleal). It's documented. MSDN (on LoadString):

          nBufferMax [in] int The size of the buffer, in characters. The string is truncated and null-terminated if it is longer than the number of characters specified. If this parameter is 0, then lpBuffer receives a read-only pointer to the resource itself.

          Secondly, I tried it (after reading the documentation thoroughly first) and verified that it did work. Finally, your technique will not work. LoadResource returns nothing that LoadString can consume.

          Steve

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          L Offline
          Lost User
          wrote on last edited by
          #13

          Stephen Hewitt wrote:

          Finally, your technique will not work. LoadResource returns nothing that LoadString can consume.

          Hi Stephen, You may be correct. I was thinking that you could just do something like this:

          HRSRC hres = FindResource(NULL, MAKEINTRESOURCE(IDS_SOMESTRING), RT_STRING);
          DWORD dwSizeRes = SizeofResource(NULL,hres);
          char *p = NULL;
          int result = LoadString((HINSTANCE)&__ImageBase,AFX_IDS_APP_TITLE,p,0);
          std::string s(p,dwSizeRes);
          

          Which is not much different than what you posted. With the method that you posted...I am thinking that the std::string would need a NULL terminator in the string resource. I admit that I have not tried either method (including the one I just typed above). I will test both methods later when I get some free time. Best Wishes, -David Delaune

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          • S Stephen Hewitt

            It does for a wstring (which was all it was intended to, it wasn't a reply to the OP but to Aescleal). It's documented. MSDN (on LoadString):

            nBufferMax [in] int The size of the buffer, in characters. The string is truncated and null-terminated if it is longer than the number of characters specified. If this parameter is 0, then lpBuffer receives a read-only pointer to the resource itself.

            Secondly, I tried it (after reading the documentation thoroughly first) and verified that it did work. Finally, your technique will not work. LoadResource returns nothing that LoadString can consume.

            Steve

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            L Offline
            Lost User
            wrote on last edited by
            #14

            Hey Steve :) I just spent 30 minutes testing both of our code samples. I could not get the code you wrote working for std::string probably because the resource strings are actually stored in Unicode within the PE files. However for wstrings your code is absolutely perfect. I suspect... that the brilliant code you posted could be actually be modified to utilize wcstombs and work for both ANSI and Unicode builds. As for my code sample... I had even less success although I was eventually able to get it working. I had to re-read some of the MSDN docs and ended up using FindResourceEx with the language identifier. To make things worse the address I was recieving was the start of the string resource block. I had to load the string block into an HGLOBAL and walk the string table before I could even read the string. :doh: Anyway I just wanted to let you know that you were correct. :) Best Wishes, -David Delaune

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            • G gmallax

              Hi, CString sz; sz.LoadString( HINSATANCE hin,UINT id); How to achieve the above thing by using std::string instead of cstring??? Thanx.

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              Alain Rist
              wrote on last edited by
              #15

              See my answer including Stephen Hewitt contribution at http://www.codeproject.com/Tips/86496/Load-a-Windows-string-resource-into-a-std-string-o.aspx[^] cheers, AR

              When the wise (person) points at the moon the fool looks at the finger (Chinese proverb)

              G 2 Replies Last reply
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              • L Lost User

                Hey Steve :) I just spent 30 minutes testing both of our code samples. I could not get the code you wrote working for std::string probably because the resource strings are actually stored in Unicode within the PE files. However for wstrings your code is absolutely perfect. I suspect... that the brilliant code you posted could be actually be modified to utilize wcstombs and work for both ANSI and Unicode builds. As for my code sample... I had even less success although I was eventually able to get it working. I had to re-read some of the MSDN docs and ended up using FindResourceEx with the language identifier. To make things worse the address I was recieving was the start of the string resource block. I had to load the string block into an HGLOBAL and walk the string table before I could even read the string. :doh: Anyway I just wanted to let you know that you were correct. :) Best Wishes, -David Delaune

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                Stephen Hewitt
                wrote on last edited by
                #16

                Thanks.

                Steve

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                • A Alain Rist

                  See my answer including Stephen Hewitt contribution at http://www.codeproject.com/Tips/86496/Load-a-Windows-string-resource-into-a-std-string-o.aspx[^] cheers, AR

                  When the wise (person) points at the moon the fool looks at the finger (Chinese proverb)

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                  gmallax
                  wrote on last edited by
                  #17

                  Very nice and useful..Thanx :)

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                  • G gmallax

                    Very nice and useful..Thanx :)

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                    Alain Rist
                    wrote on last edited by
                    #18

                    gmallax wrote:

                    Very nice and useful

                    Then please upvote. Thanks, AR

                    When the wise (person) points at the moon the fool looks at the finger (Chinese proverb)

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                    • A Alain Rist

                      See my answer including Stephen Hewitt contribution at http://www.codeproject.com/Tips/86496/Load-a-Windows-string-resource-into-a-std-string-o.aspx[^] cheers, AR

                      When the wise (person) points at the moon the fool looks at the finger (Chinese proverb)

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                      gmallax
                      wrote on last edited by
                      #19

                      hi, here we declare char buffer as char buffer[ 1024 ] = { '\0' }.. How to release this?

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                      • G gmallax

                        hi, here we declare char buffer as char buffer[ 1024 ] = { '\0' }.. How to release this?

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                        Alain Rist
                        wrote on last edited by
                        #20

                        It is released at the next }

                        ReturnType SomeClass::SomeFunction(SomeParams)
                        {
                        char buffer[1024] = {0}; // this a stack allocation
                        // any code ...
                        return ReturnType::SomeValue;
                        } // buffer is deallocated here

                        cheers, AR

                        When the wise (person) points at the moon the fool looks at the finger (Chinese proverb)

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