CodeGuru Home VC++ / MFC / C++ .NET / C# Visual Basic VB Forums Developer.com
Page 1 of 2 12 LastLast
Results 1 to 15 of 23
  1. #1
    Join Date
    Oct 2007
    Location
    Baroda,India
    Posts
    74

    Copying from unsigned char * to the CString

    Hi All,

    I have unsigned char * buffer in which some data are stored , now I want to move these all data to my CString variable for some operations.

    I tried to copy but problem is that in my unsigned char * some data are padded as zero, So I hope that in CString it gets the null value so it can not copy whole data.

    I tried to copy from unsigned char * to the CString using...

    CString tmpMsg = CString(msg); // Here msg is the unsigned char *

    Ashish

  2. #2
    Join Date
    May 2002
    Posts
    1,435

    Re: Copying from unsigned char * to the CString

    Don't try to use CString for containing binary data - it won't work. Tell us more about what you are doing and we can suggest alternatives.

  3. #3
    Join Date
    Oct 2002
    Location
    Timisoara, Romania
    Posts
    14,360

    Re: Copying from unsigned char * to the CString

    So you want to copy a buffer to a CString variable and want to keep the characters that are set to 0. So that the string was something like this 'ABC\0\0DEF'. Is that correct?
    Marius Bancila
    Home Page
    My CodeGuru articles

    I do not offer technical support via PM or e-mail. Please use vbBulletin codes.

  4. #4
    Join Date
    Oct 2007
    Location
    Baroda,India
    Posts
    74

    Re: Copying from unsigned char * to the CString

    In my unsigned char * buffer I have all char data, so I want all these data into my CString variable.

    I tried to use memcpy() ,but it gives me the runtime error like....


    TestRTMP.exe: 0xC0000005: Access violation reading location 0x49468964.


    so plz help me.

    Thanks.

  5. #5
    Join Date
    Oct 2007
    Location
    Baroda,India
    Posts
    74

    Re: Copying from unsigned char * to the CString

    Quote Originally Posted by cilu
    So you want to copy a buffer to a CString variable and want to keep the characters that are set to 0. So that the string was something like this 'ABC\0\0DEF'. Is that correct?
    when 0 value comes in CString it shows nothig(Just like blank space)...

    I m not getting that to much,but the problem is of zero value.

  6. #6
    Join Date
    May 2002
    Posts
    1,435

    Re: Copying from unsigned char * to the CString

    While it is technically possible to store a binary 0 in a CString you should not do it. There are too many problems that will be encountered. The bottom line is that most of the CString member functions (including the constructor you are trying to use) assume binary 0 is the end-of-string terminator and will fail for whatever purpose you intend. Once again, you need to re-think your application and use a container other than CString.

  7. #7
    Join Date
    Aug 2001
    Location
    Germany
    Posts
    1,384

    Re: Copying from unsigned char * to the CString

    0xC0000005 is right, my suggestion is to use std::string for that purpose.

    Regards,
    Usman.

  8. #8
    Join Date
    Feb 2003
    Location
    Iasi - Romania
    Posts
    8,234

    Re: Copying from unsigned char * to the CString

    Although it's not a very brilliant idea, you can store any character including '\0' in a CString object as follows
    Code:
    void CFoo::FillString(CString& str, unsigned char* msg, int length)
    {
       char* buffer = str.GetBufferSetLength(length);
       memcpy(buffer, msg, length);
       str.ReleaseBuffer(length);
    }
    With one condition: use that object only for storing; another subsequent call of one of CString methods may truncate it to the first '\0' value.
    Last edited by ovidiucucu; October 19th, 2007 at 09:11 AM.
    Ovidiu
    "When in Rome, do as Romans do."
    My latest articles: https://codexpertro.wordpress.com/

  9. #9
    Join Date
    Feb 2003
    Location
    Iasi - Romania
    Posts
    8,234

    Re: Copying from unsigned char * to the CString

    Quote Originally Posted by usman999_1
    0xC0000005 is right, my suggestion is to use std::string for that purpose.
    UUUghhh!

  10. #10
    Join Date
    Aug 2001
    Location
    Germany
    Posts
    1,384

    Re: Copying from unsigned char * to the CString

    Quote Originally Posted by ovidiucucu
    UUUghhh!

  11. #11
    GCDEF is offline Elite Member Power Poster
    Join Date
    Nov 2003
    Location
    Florida
    Posts
    12,635

    Re: Copying from unsigned char * to the CString

    I wouldn't use any kind of string, std, CString or anything else you find to store data that contains a NULL.

  12. #12
    Join Date
    Feb 2003
    Location
    Iasi - Romania
    Posts
    8,234

    Re: Copying from unsigned char * to the CString

    Right.
    A possible better approach is to write your own "buffer" class like for example:
    Code:
    class CBuffer
    {
       unsigned char* buffer;
       unsigned int length;
    public:
       CBuffer() : buffer(NULL), length(0) {};
       SetBuffer(unsigned char* src, unsigned int length); 
       unsigned int GetLength() const {return length;}
       // and so on, and so on... all you need
    };
    Ovidiu
    "When in Rome, do as Romans do."
    My latest articles: https://codexpertro.wordpress.com/

  13. #13
    Join Date
    Aug 2001
    Location
    Germany
    Posts
    1,384

    Re: Copying from unsigned char * to the CString

    Quote Originally Posted by GCDEF
    I wouldn't use any kind of string, std, CString or anything else you find to store data that contains a NULL.
    What's wrong with std::string???

  14. #14
    Join Date
    Feb 2003
    Location
    Iasi - Romania
    Posts
    8,234

    Re: Copying from unsigned char * to the CString

    Quote Originally Posted by usman999_1
    What's wrong with std::string???
    Why do you think it's better than CString?

  15. #15
    Join Date
    Aug 2000
    Location
    West Virginia
    Posts
    7,721

    Re: Copying from unsigned char * to the CString

    What is the advantage of writing your own buffer class instead
    of using std::string ???????????????????????

Page 1 of 2 12 LastLast

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •  





Click Here to Expand Forum to Full Width

Featured