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Copy Hex from String

Posted on 2004-03-22
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Last Modified: 2008-02-01
Hello

I have 6 Edit controls in which the user enters a hex value (for example the string "00" in edit 1 "e1" in edit 2 etc)

      UCHAR szDestMac[6] = {NULL}; //This is the varaible in which I want to store all my hex numbers

                //I get the text from the edit box as follows
                TCHAR m_szDestMAC[3];
      GetDlgItemText(IDC_EDIT_SRCMAC1, m_szDestMAC, sizeof(m_szDestMAC));
               
                //So now m_szDestMAC = "00" and I want to copy this as a hex number into the first byte of my unicode array, szDestMac[0].

                //I tried both the following
      swprintf((TCHAR*)&szDestMac[0], _T("%s"), m_szDestMAC);
      //memcpy(&szDestMac[0], m_szDestMAC, 1);

                //But the TRACE statment returns as "Got Source MAC from user: 30"
      TRACE(_T("Got Source MAC from user: %02x\n"), szDestMac[0]);

Anyone know why szDestMac[0] contains the value 30 instead of what was typed in the edit control "00" and how to resolve the problem

Regards
 
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Question by:auk_ie
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5 Comments
 
LVL 23

Assisted Solution

by:chensu
chensu earned 50 total points
ID: 10651279
0x30 is the ASCII value of character '0'. If you want to print out the character,

TRACE(_T("Got Source MAC from user: %c\n"), szDestMac[0]);
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LVL 86

Assisted Solution

by:jkr
jkr earned 50 total points
ID: 10651307
Try

swprintf((TCHAR*)&szDestMac[0], _T("%S"), m_szDestMAC);  // note the capital 'S'

Are you sure you don't want to use sth. like

UCHAR szDestMac[7] = {0,0,0,0,0,0,0};

<loop from 0 to 6>
    TCHAR m_szDestMAC[3];
    GetDlgItemText(IDC_EDIT_SRCMAC1, m_szDestMAC, sizeof(m_szDestMAC));
    wchar_t wszTmp  [3];
    wsprintf ( wszTmp, "%S", m_szDestMac);
    wcscat ( szDestMac, wszTmp);
<end loop>





0
 
LVL 23

Expert Comment

by:brettmjohnson
ID: 10651327
swprintf() is not what you want you use as this point.
You want to use strtol() instead:

szDestMac[0] = (UCHAR) strtol(m_szDestMAC);


0
 
LVL 23

Expert Comment

by:chensu
ID: 10651395
The code should be like this,

TCHAR szDestMac[6] = { 0 };

TCHAR m_szDestMAC[3];
GetDlgItemText(IDC_EDIT_SRCMAC1, m_szDestMAC, sizeof(m_szDestMAC) / sizeof(TCHAR));
               
_stprintf(szDestMac, _T("%s"), m_szDestMAC);

TRACE(_T("Got Source MAC from user: %c\n"), szDestMac[0]);

Note that the MFC documentation on CWnd::GetDlgItemText() is wrong.

"nMaxCount
Specifies the maximum length (in bytes) of the string to be copied to lpStr. If the string is longer than nMaxCount, it is truncated."

It should be in characters rather than bytes.
0
 
LVL 23

Accepted Solution

by:
brettmjohnson earned 400 total points
ID: 10651548
> szDestMac[0] = (UCHAR) strtol(m_szDestMAC);

Oops, my bad.  that should be:

szDestMac[0] = (UCHAR) strtol(m_szDestMAC, NULL, 16);

0

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