Re: LPCWSTR to CString conversion problem

From:

=?Utf-8?B?Um9oaXQgS3VtYXI=?= <RohitKumar@discussions.microsoft.com>

Newsgroups:

microsoft.public.vc.atl

Date:

Mon, 9 Jul 2007 06:22:01 -0700

Message-ID:

<9D53B22C-65BD-4747-A545-6DC88F069A66@microsoft.com>

I am trying out the following program...

////////////////////////////////////////////////////////////////////////////////////////////////
<config>
    <key name="first" value="1250A"/>
    <key name="second" value="1250B"/>
</config>

And I want to read a value of a key named "foo":

#include "stdafx.h"
#include <atlbase.h>
#include "xmllite.h"
#include <strsafe.h>

int _tmain(int argc, _TCHAR* argv[])
{
  HRESULT hr;
  CComPtr<IStream> pFileStream;
  CComPtr<IXmlReader> pReader;
  XmlNodeType nodeType;
  const WCHAR* pName;
  const WCHAR* pValue;

  //Open XML document
  if (FAILED(hr = SHCreateStreamOnFile(L"config.xml",
    STGM_READ, &pFileStream)))
  {
    wprintf(L"Error opening XML document, error %08.8lx", hr);
    return -1;
  }

  if (FAILED(hr = CreateXmlReader(__uuidof(IXmlReader),
    (void**)&pReader, NULL)))
  {
    wprintf(L"Error creating XmlReader, error %08.8lx", hr);
    return -1;
  }

  if (FAILED(hr = pReader->SetInput(pFileStream)))
  {
    wprintf(L"Error setting input for XmlReader, error %08.8lx", hr);
    return -1;
  }

  while (S_OK == (hr = pReader->Read(&nodeType)))
  {
    switch (nodeType)
    {
    case XmlNodeType_Element:
      if (FAILED(hr = pReader->GetQualifiedName(&pName, NULL)))

      {
        wprintf(L"Error reading element name, error %08.8lx", hr);
        return -1;
      }
      if (wcscmp(pName, L"key") == 0)
      {
        if (SUCCEEDED(hr =
          pReader->MoveToAttributeByName(L"name", NULL)))

        {
          if (FAILED(hr = pReader->GetValue(&pValue, NULL)))

          {
            wprintf(L"Error reading attribute value, error %08.8lx", hr);
            return -1;
          }
          if (wcscmp(pValue, L"foo") == 0)
          {
            //That's an element we are looking for
            if (FAILED(hr =
              pReader->MoveToAttributeByName(L"value", NULL)))

            {
              wprintf(L"Error reading attribute \"value\", error %08.8lx",
hr);
              return -1;
            }
            if (FAILED(hr = pReader->GetValue(&pValue, NULL)))

            {
              wprintf(L"Error reading attribute value, error %08.8lx", hr);
              return -1;
            }
            wprintf(L"Key \"foo\"'s value is \"%s\" ", pValue);
          }
        }
      }
      break;
    }
  }
  return 0;
}
////////////////////////////////////////////////////////////////////////////////////////////////

I am using the above program with some modifications.

if (FAILED(hr = pReader->GetValue(&pValue, NULL)))

here pValue has the value "1280.50A." and i assign it to a cstring NewV.
There are no errors.

Then i use the following piece f code

for(i=0;i<NewV.GetLength();i++)
    {
       if(isdigit(NewV.GetAt(i)) == FALSE)
        {
            hasAlpha = TRUE;
        }
     }

But when i is 0, then the if loop gets executed where it should have not
entered. I hope you got where the problem is. Using iswdigit doesnt help
either. My project is in unicode.

Thanks,
Rohit.

"SvenC" wrote:

Hi,

sorry i intended to write getat(0). My cstring variable NewVersion which
contains the return value of GetValue() function has the value
"1280.50.". I get the first character of the string and pass it to
isdigit(). But it returns false. I guess there is some problem with the
LPCWSTR to CString conversion. When i manually initialize the NewVersion
as NewVersion = "1280.50.", then the first character wen passed to
isdigit() returns true.

Please show your code.
Do you compile as Unicode or Ansi? If Unicode use iswdigit to test a single
character.

--
SvenC

"Igor Tandetnik" wrote:

"Rohit Kumar" <RohitKumar@discussions.microsoft.com> wrote in message
news:95D7082C-4540-41A2-B485-E866F903C030@microsoft.com

I am using xmllite methods for reading from an xml file inside my
interface method. There is a function IXmlReader::GetValue which
returns the value of the xml element. The return value is an LPCWSTR.
When i try assigning it to a CString and use the first element of
that cstring using getat(1) then it returns a garbage value.

GetAt(1) returns the second character of the string, not the first. Are
you sure the string is long enough? What exactly do you mean by "garbage
value"?
--
With best wishes,
Igor Tandetnik

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