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  4. _variant_t to CString

_variant_t to CString

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  • S Stuart Dootson

    In VS2008, this should do the job...

    _variant_t v;
    // Set a value in v
    CString s = v;

    CString has assignment operator and constructor overl;oads that take a const VARIANT&. _variant_t has an extrractor that returns a VARIANT.

    Java, Basic, who cares - it's all a bunch of tree-hugging hippy cr*p

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    R Offline
    rdop
    wrote on last edited by
    #6

    Plz help me some one

    S 1 Reply Last reply
    0
    • R rdop

      Hi All How can i convert _variant_t to CString?

      L Offline
      L Offline
      Lost User
      wrote on last edited by
      #7

      Hi rdop, The following snippit will work on all Microsoft compilers:_variant_t v; v = 3.141; ::VariantChangeType(&v, &v, 0, VT_BSTR); CString s = (LPTSTR)(_bstr_t)v.bstrVal;
      Best Wishes, -David Delaune

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      • R rdop

        Plz help me some one

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        Stuart Dootson
        wrote on last edited by
        #8

        I (and Microsoft, who wrote the _variant_t and CString code) have helped you - you just assign the _variant_t to the CString - what more do you want?!?!?!?!?

        Java, Basic, who cares - it's all a bunch of tree-hugging hippy cr*p

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        • S Stuart Dootson

          Noooooo - you don't need to bother with that - there's a VariantChangeType function that'll do that for you when you convert a VARIANT to a BSTR. And even more conveniently, the combination of _variant_t extractor operators and CString constructors will do all that for you. A simple assignment of _variant_t to CString is all that's needed...

          Java, Basic, who cares - it's all a bunch of tree-hugging hippy cr*p

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          C Offline
          CPallini
          wrote on last edited by
          #9

          Nice to know :thumbsup:. What about _variant_t containing arrays? :)

          If the Lord God Almighty had consulted me before embarking upon the Creation, I would have recommended something simpler. -- Alfonso the Wise, 13th Century King of Castile.
          This is going on my arrogant assumptions. You may have a superb reason why I'm completely wrong. -- Iain Clarke
          [My articles]

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          • S Stuart Dootson

            I (and Microsoft, who wrote the _variant_t and CString code) have helped you - you just assign the _variant_t to the CString - what more do you want?!?!?!?!?

            Java, Basic, who cares - it's all a bunch of tree-hugging hippy cr*p

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            rdop
            wrote on last edited by
            #10

            See what happen.

            _variant_t vtValue;
            vtValue = m_pRset->Fields->GetItem("Bianry")->GetValue();
            CString b=vtValue;
            output is b = "??4"
            when i copy the vtValues at the time of debug then i got values
            safearray of UI1 = [20](54 '6',53 '5',52 '4',54 '6',52 '4',0,0,0,0,0,0,0,0,0,0,0,0,0,0,0)

            Any more information if you nedd then i will give you.

            S 1 Reply Last reply
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            • R rdop

              Thanks for responce.I hava a biray type data in _variant_t. _variant_t v1; v1=(54 '6',53 '5',52 '4',54 '6',52 '4',0,0,0,0,0,0,0,0,0,0,0,0,0,0,0); Can i convert these values in CString or not. Origal values is"65464". Plz help me

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              C Offline
              CPallini
              wrote on last edited by
              #11

              What is v1.vt value? :)

              If the Lord God Almighty had consulted me before embarking upon the Creation, I would have recommended something simpler. -- Alfonso the Wise, 13th Century King of Castile.
              This is going on my arrogant assumptions. You may have a superb reason why I'm completely wrong. -- Iain Clarke
              [My articles]

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              • R rdop

                See what happen.

                _variant_t vtValue;
                vtValue = m_pRset->Fields->GetItem("Bianry")->GetValue();
                CString b=vtValue;
                output is b = "??4"
                when i copy the vtValues at the time of debug then i got values
                safearray of UI1 = [20](54 '6',53 '5',52 '4',54 '6',52 '4',0,0,0,0,0,0,0,0,0,0,0,0,0,0,0)

                Any more information if you nedd then i will give you.

                S Offline
                S Offline
                Stuart Dootson
                wrote on last edited by
                #12

                As it's an array, VariantChangeType's not going to work. So, I'd suggest the code below. I'm assuming you want to access the non-null characters of the array and make them into a string?

                CComSafeArray<char, VT_UI1> sa(V_ARRAY(&v));
                CString s;
                for(int index=sa.GetLowerBound();index<=sa.GetUpperBound()&&sa[index];++index)
                {
                s+=sa[index];
                }

                [edit] You'll also need to #include atlsafe.h and oleauto.h [/edit]

                Java, Basic, who cares - it's all a bunch of tree-hugging hippy cr*p

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                • C CPallini

                  Nice to know :thumbsup:. What about _variant_t containing arrays? :)

                  If the Lord God Almighty had consulted me before embarking upon the Creation, I would have recommended something simpler. -- Alfonso the Wise, 13th Century King of Castile.
                  This is going on my arrogant assumptions. You may have a superb reason why I'm completely wrong. -- Iain Clarke
                  [My articles]

                  S Offline
                  S Offline
                  Stuart Dootson
                  wrote on last edited by
                  #13

                  CPallini wrote:

                  What about _variant_t containing arrays?

                  Use CComSafeArray[^].

                  _variant_t v;
                  // Assign a SAFEARRAY value to v
                  CComSafeArray<char, VT_UI1> sa(V_ARRAY(&v));
                  // Now we can access the SAFEARRAY using sa.

                  Java, Basic, who cares - it's all a bunch of tree-hugging hippy cr*p

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                  • S Stuart Dootson

                    As it's an array, VariantChangeType's not going to work. So, I'd suggest the code below. I'm assuming you want to access the non-null characters of the array and make them into a string?

                    CComSafeArray<char, VT_UI1> sa(V_ARRAY(&v));
                    CString s;
                    for(int index=sa.GetLowerBound();index<=sa.GetUpperBound()&&sa[index];++index)
                    {
                    s+=sa[index];
                    }

                    [edit] You'll also need to #include atlsafe.h and oleauto.h [/edit]

                    Java, Basic, who cares - it's all a bunch of tree-hugging hippy cr*p

                    L Offline
                    L Offline
                    Lost User
                    wrote on last edited by
                    #14

                    Hi Stuart, What do you think about this VT_UI1 SAFEARRAY to CStringA conversion method?BSTR b; BstrFromVector(pSA,&b); CStringA s = (LPCSTR)b;
                    Best Wishes, -David Delaune

                    S 1 Reply Last reply
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                    • L Lost User

                      Hi Stuart, What do you think about this VT_UI1 SAFEARRAY to CStringA conversion method?BSTR b; BstrFromVector(pSA,&b); CStringA s = (LPCSTR)b;
                      Best Wishes, -David Delaune

                      S Offline
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                      Stuart Dootson
                      wrote on last edited by
                      #15

                      New to me - that'll teach me to do what I've told many other people to do and read the documentation :laugh: And of course it'll work with wide CStrings as well.

                      Java, Basic, who cares - it's all a bunch of tree-hugging hippy cr*p

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                      • S Stuart Dootson

                        As it's an array, VariantChangeType's not going to work. So, I'd suggest the code below. I'm assuming you want to access the non-null characters of the array and make them into a string?

                        CComSafeArray<char, VT_UI1> sa(V_ARRAY(&v));
                        CString s;
                        for(int index=sa.GetLowerBound();index<=sa.GetUpperBound()&&sa[index];++index)
                        {
                        s+=sa[index];
                        }

                        [edit] You'll also need to #include atlsafe.h and oleauto.h [/edit]

                        Java, Basic, who cares - it's all a bunch of tree-hugging hippy cr*p

                        R Offline
                        R Offline
                        rdop
                        wrote on last edited by
                        #16

                        thanks it's working for me.

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