Copying CByteArray to a CString?
in [MFC]
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From: Tom Serface on 2 Oct 2009 11:11 Try something like: CString myString; LPTSTR p = myString.GetBuffer( buffer.GetSize() +1 ); loop through p and buffer add your characters myString.ReleaseBuffer(); Tom "Eddards" <eddards(a)verizon.net> wrote in message news:9Y-dnUoO85ysiVvXnZ2dnUVZ_gednZ2d(a)giganews.com... > OK so now I have the following: > > for (i=0; i<buffer.GetSize(); i++){ > if (buffer[i] == 0x00) > buffer[i] = 0x01; > } > CString CipStr((LPCSTR)buffer.GetData(), buffer.GetSize()); > > Compiler error: > error C2064: term does not evaluate to a function > > > "Joseph M. Newcomer" <newcomer(a)flounder.com> wrote in message > news:op2cc51p1oorq1s13h5g4us37ktgauv5nm(a)4ax.com... >> Because you did something truly silly: :you did +=. This means the >> second time through, >> it has to make a copy of a 1-character ClipStr; the third time through it >> has to make a >> copy of a 2-ClipStr ClipStr, the fourth time through it has to make a >> copy of a >> 3-character ClipStr, and each time it goes through it has to make a copy! >> This is called >> the "exponential copy problem", and you must have a very fast machine if >> it only took a >> minute. By the 4,200,001 iteration it was copying a string of 4,200,000 >> characters, then >> appending a character to that, then copying 4,200,001 characters and >> appending a >> character to that, and so on. This requires an allocation, which must be >> initialized, >> then a massive copy, only to, a few nanoseconds later, repeat this >> lengthy process. >> >> The CORRECT code would have been to run through and change all the bytes, >> and THEN make >> PRECISELY ONE copy, at the end! >> >> Note that you also failed in describing a problem: you didn't give all >> the critical >> information! String length is a critical parameter! >> >> for(int i = 0; i < buffer.GetSize(); i++) >> { >> if(buffer[i] = 0x00) >> buffer[i] = 0x01; >> } >> >> CString CipStr((LPCSTR)buffer.GetData(), buffer.GetSize()); >> >> This makes only one copy. >> joe >> >> On Fri, 2 Oct 2009 08:23:49 -0400, "Eddards" <eddards(a)verizon.net> wrote: >> >>>This is what I have. >>>The size of the file read into buffer was 4.6mb >>>Why does it take so long to run through? (over a minute). >>> >>> int i; >>> CString CipStr; >>> for (i=0; i<buffer.GetSize(); i++){ >>> if (buffer[i] == 0x00) >>> buffer[i] = 0x01; >>> CipStr += buffer[i]; >>> } >>> >>> >>>"Eddards" <eddards(a)verizon.net> wrote in message >>>news:KpidnfDBIMVReljXnZ2dnUVZ_uOdnZ2d(a)giganews.com... >>>>I tried copying the buffer with a loop like you show below. >>>> It took over a minute to process all 4,000,000 bytes. >>>> Dont know why it should take so long. >>>> >>>> >>>> "Joseph M. Newcomer" <newcomer(a)flounder.com> wrote in message >>>> news:57sac5hc63e673ijs0fdttud2annvadrno(a)4ax.com... >>>>> for(int i = 0; i < buffer.GetSize(); i++) >>>>> if(buffer[i] == 0x00) >>>>> buffer[i] = 0x01; >>>>> >>>>> What is so hard about this? This is pretty elementary C programming! >>>>> >>>>> If you want to do it more along the "hard way" read about the >>>>> MultiByteToWideChar API (and >>>>> see my essay on my MVP Tips site on CString techniques) >>>>> >>>>> joe >>>>> On Thu, 1 Oct 2009 15:09:07 -0400, "Eddards" <eddards(a)verizon.net> >>>>> wrote: >>>>> >>>>>>I also need to replace any 0x00 (NULL) chars with 0x01 when copying to >>>>>>the >>>>>>CString >>>>>>Is this possible ? >>>>>> >>>>>>"Eddards" <eddards(a)verizon.net> wrote in message >>>>>>news:9fGdnWZaLPg3J1nXnZ2dnUVZ_u6dnZ2d(a)giganews.com... >>>>>>>I am using VC6. >>>>>>> Is there a way to copy a CByteArray to a CString? >>>>>>> >>>>>>> >>>>>> >>>>> Joseph M. Newcomer [MVP] >>>>> email: newcomer(a)flounder.com >>>>> Web: http://www.flounder.com >>>>> MVP Tips: http://www.flounder.com/mvp_tips.htm >>>> >>>> >>> >> Joseph M. Newcomer [MVP] >> email: newcomer(a)flounder.com >> Web: http://www.flounder.com >> MVP Tips: http://www.flounder.com/mvp_tips.htm > >
From: Giovanni Dicanio on 2 Oct 2009 11:41 "Eddards" <eddards(a)verizon.net> ha scritto nel messaggio news:9Y-dnUoO85ysiVvXnZ2dnUVZ_gednZ2d(a)giganews.com... > OK so now I have the following: > > for (i=0; i<buffer.GetSize(); i++){ > if (buffer[i] == 0x00) > buffer[i] = 0x01; > } > CString CipStr((LPCSTR)buffer.GetData(), buffer.GetSize()); > > Compiler error: > error C2064: term does not evaluate to a function I second the idea of using CString::GetBuffer/ReleaseBuffer. You may want to try this code, which seems to compile and work fine: <code> CByteArray buffer; ... fill the buffer or something ... // Index for buffer looping int i; // Change 0x00 bytes in buffer to 0x01 for (i = 0; i < buffer.GetSize(); i++) { if (buffer[i] == 0x00) buffer[i] = 0x01; } // Copy buffer content to a CString instance CString str; LPTSTR psz = str.GetBuffer( buffer.GetSize() + 1 ); for (i = 0; i < buffer.GetSize(); i++) { psz[i] = buffer[i]; } psz[i] = 0; // end of string str.ReleaseBuffer(); // Show the string AfxMessageBox(str); </code> Note that we are just raw-copying the byte array content to the CString, but you should be sure about the encoding of the text data stored in the byte array (is this ANSI? Or UTF-8? Or some other code page?) Giovanni
From: Joseph M. Newcomer on 2 Oct 2009 12:15 I'm sure that error message has a line associated with it... It has been years since I used VS6, but I fired it up and used the code shown below, modified the project settings to compile as Unicode, and looked at the memory results: CByteArray buffer; buffer.SetSize(4); buffer[0] = 'A'; buffer[1] = 'B'; buffer[2] = 'C'; buffer[3] = 'D'; CString s((LPCSTR)buffer.GetData(), buffer.GetSize()); buffer.GetData(): 00326D78 41 42 43 44 FD FD FD FD 0D s.GetBuffer(): 00326DCC 41 00 42 00 43 00 44 00 00 So it compiles and executes correctly. joe On Fri, 2 Oct 2009 10:54:42 -0400, "Eddards" <eddards(a)verizon.net> wrote: >OK so now I have the following: > > for (i=0; i<buffer.GetSize(); i++){ > if (buffer[i] == 0x00) > buffer[i] = 0x01; > } > CString CipStr((LPCSTR)buffer.GetData(), buffer.GetSize()); > >Compiler error: >error C2064: term does not evaluate to a function > > >"Joseph M. Newcomer" <newcomer(a)flounder.com> wrote in message >news:op2cc51p1oorq1s13h5g4us37ktgauv5nm(a)4ax.com... >> Because you did something truly silly: :you did +=. This means the second >> time through, >> it has to make a copy of a 1-character ClipStr; the third time through it >> has to make a >> copy of a 2-ClipStr ClipStr, the fourth time through it has to make a copy >> of a >> 3-character ClipStr, and each time it goes through it has to make a copy! >> This is called >> the "exponential copy problem", and you must have a very fast machine if >> it only took a >> minute. By the 4,200,001 iteration it was copying a string of 4,200,000 >> characters, then >> appending a character to that, then copying 4,200,001 characters and >> appending a >> character to that, and so on. This requires an allocation, which must be >> initialized, >> then a massive copy, only to, a few nanoseconds later, repeat this lengthy >> process. >> >> The CORRECT code would have been to run through and change all the bytes, >> and THEN make >> PRECISELY ONE copy, at the end! >> >> Note that you also failed in describing a problem: you didn't give all the >> critical >> information! String length is a critical parameter! >> >> for(int i = 0; i < buffer.GetSize(); i++) >> { >> if(buffer[i] = 0x00) >> buffer[i] = 0x01; >> } >> >> CString CipStr((LPCSTR)buffer.GetData(), buffer.GetSize()); >> >> This makes only one copy. >> joe >> >> On Fri, 2 Oct 2009 08:23:49 -0400, "Eddards" <eddards(a)verizon.net> wrote: >> >>>This is what I have. >>>The size of the file read into buffer was 4.6mb >>>Why does it take so long to run through? (over a minute). >>> >>> int i; >>> CString CipStr; >>> for (i=0; i<buffer.GetSize(); i++){ >>> if (buffer[i] == 0x00) >>> buffer[i] = 0x01; >>> CipStr += buffer[i]; >>> } >>> >>> >>>"Eddards" <eddards(a)verizon.net> wrote in message >>>news:KpidnfDBIMVReljXnZ2dnUVZ_uOdnZ2d(a)giganews.com... >>>>I tried copying the buffer with a loop like you show below. >>>> It took over a minute to process all 4,000,000 bytes. >>>> Dont know why it should take so long. >>>> >>>> >>>> "Joseph M. Newcomer" <newcomer(a)flounder.com> wrote in message >>>> news:57sac5hc63e673ijs0fdttud2annvadrno(a)4ax.com... >>>>> for(int i = 0; i < buffer.GetSize(); i++) >>>>> if(buffer[i] == 0x00) >>>>> buffer[i] = 0x01; >>>>> >>>>> What is so hard about this? This is pretty elementary C programming! >>>>> >>>>> If you want to do it more along the "hard way" read about the >>>>> MultiByteToWideChar API (and >>>>> see my essay on my MVP Tips site on CString techniques) >>>>> >>>>> joe >>>>> On Thu, 1 Oct 2009 15:09:07 -0400, "Eddards" <eddards(a)verizon.net> >>>>> wrote: >>>>> >>>>>>I also need to replace any 0x00 (NULL) chars with 0x01 when copying to >>>>>>the >>>>>>CString >>>>>>Is this possible ? >>>>>> >>>>>>"Eddards" <eddards(a)verizon.net> wrote in message >>>>>>news:9fGdnWZaLPg3J1nXnZ2dnUVZ_u6dnZ2d(a)giganews.com... >>>>>>>I am using VC6. >>>>>>> Is there a way to copy a CByteArray to a CString? >>>>>>> >>>>>>> >>>>>> >>>>> Joseph M. Newcomer [MVP] >>>>> email: newcomer(a)flounder.com >>>>> Web: http://www.flounder.com >>>>> MVP Tips: http://www.flounder.com/mvp_tips.htm >>>> >>>> >>> >> Joseph M. Newcomer [MVP] >> email: newcomer(a)flounder.com >> Web: http://www.flounder.com >> MVP Tips: http://www.flounder.com/mvp_tips.htm > Joseph M. Newcomer [MVP] email: newcomer(a)flounder.com Web: http://www.flounder.com MVP Tips: http://www.flounder.com/mvp_tips.htm
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