IsNumeric Check

IsNumeric Check

• Udhaya Kumar D

  Hey,
  
  thanks for your help. The isdigit method works.  I have a string something like 1234, i wanted to check that each part of the string was numeric, as i will breaking it up for various reasons.  so..
  
  CString s = _T("1234");
  for (int a = 0; a<s.GetLength;a++)
  {
     if (isdigit(s.GetAt(a))
     {
     //code
     }//if
  }//for
  
  That works
  
  Thanks for your help
  
  Will

  
  

• VB 2005 Technical Support

  I can't think of one off my head so I did a quick search on the internet and the following linkp http://www.functionx.com/visualc/libraries/mfcstaticlib.htm provided an implementation of BOOL IsNumeric(const CString Str)
  
  Also, you might want to take a look at http://msdn2.microsoft.com/en-us/library/c707ct0t(en-US,VS.80).aspx if it is helpful.
  
  Thanks,
    Ayman Shoukry
    VC++ Team
  
  

• XiNO

  I think there could be two approaches:
  1. IsCharAlphaNumeric && !IsCharAlpha
  These are Win32 functions, expect TCHAR arguments.
  
  2. isdigit() CRT function
  This is a CRT function. I don't know if you do not want to link with CRT.
  
  const ULONG g_ccbMaxLen = 0x2000000;  // arbitrarily, do not check strings longer than 32MB
  
  bool IsDigit(TCHAR c)
  {
  #ifdef I_DONT_WANT_CRT
       return (IsAlphaNumeric(c) && !IsNumeric(c));
  #else
       // WARNNOTE (ismailp): I am not sure, if this function works with UNICODE chars
       return isdigit(c);
  #endif
  }
  
  /*
  Return values:
  
    <0 - on failure
    >=0, number of digits
  */
  int CountDigits(LPCTSTR lpszString)
  {
      if (!lpszString)
          return -1;
      LPCTSTR lpszSeek = lpszString;
      if (lstrlen(lpszString) > g_ccbMaxLen)
            return -1;
      int iPos = 0, iCount = 0;
      for (iPos = 0; *lpszSeek && iPos < g_ccbMaxLen; ipos++, lpszSeek++)
      {
          if (IsDigit(*lpszSeek))
             ++iCount;         
      }
      return iCount;
  }
  
  bool IsNumeric(LPCTSTR lpszString)
  {
        if (!lpszString)
           return false;
        int iLen = lstrlen(lpszString);
        if (iLen == CountDigits(lpszString))
           return true;
        return false;
  }
  
  Should be ok. I have not compiled it.
  
  Ismail
  
• IsNumeric Check