CODEWITHSUNDEEP
c++c++11visual-c++mfc
Alexander Lopez
Alexander Lopez

Reputation: 127

MFC Extract CString between tags

I'm trying to code a function to retrieve the value between two tags or characters using CStrings, so far I haven't been able to do so.

CODE REMOVED

I'm pretty sure StartIndex and EndIndex have the right values, however I'm stuck at the last step, where I'm supposed to extract the substring from between the tags.

EDIT:// Got it working, thanks to Igor Tandetnik. If anyone knows why SubStr only prints correctly with wcout if I explicitly cast it with (LPCWSTR) it would be greatly appreciated. I'm leaving the working code below in case someone else needs this or wants to improve it.

CString ExtractString(CString strSource, CString strStart, CString strEnd)
{
    CString SubStr = L"";
    int iEndIndex, iStartIndex = strSource.Find(strStart);
    iStartIndex += strStart.GetLength();
    iEndIndex = strSource.Find(strEnd, iStartIndex);

    if (iStartIndex == -1 || iEndIndex == -1)
    {
        wcout << L"TAG not found!" << endl;
        return SubStr;
    }

    SubStr = strSource.Mid(iStartIndex, (iEndIndex - iStartIndex));
    SubStr.Trim();
    return SubStr;
}

Upvotes: 1

Views: 1665

Answers (1)

Barmak Shemirani
Barmak Shemirani

Reputation: 31629

If you pass std::wstring to wcout, it works fine because those guys know each other. wcout will pick the right << operator for std::wstring

But C++ Standard Library and MFC are separate. wcout doesn't know what to do with CString, so it treats CString object as const void*, it uses operator<<(const void*) to print an address.

Next step, CString returns (const wchar_t*) buffer. But wcout had already decided on const void*, so wcout prints the address of that string buffer returned by CString.

(const wchar_t*) cast will instruct wcout to use the right << operator. You can also use CString::GetString() to let wcout know that wide characters are being sent.

wcout << LPCWSTR(SubStr);
//or
wcout << SubStr.GetString();

Upvotes: 1

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