CODEWITHSUNDEEP
c++string
TheHvidsten
TheHvidsten

Reputation: 4428

Concatenating a DWORD and a LPCTSTR

I have a legacy Windows application that logs an error. It would be nice to find what kind of error is thrown, but after finding the source code for the project I realize this is C++ and I have virtually no experience with C++.

The error code is a DWORD, and the input to the log function takes a LPCTSTR.

The code is as follows right now:

DWORD dwError;
dwError = SomeFunction();

if (dwError)
{
    Log(_T("Something failed"));
}

So I would like to have the value of dwError put into the log message. Coming from a C# background I tried Log(_T("Something failed (" + dwError + ")")); but that obviously didn't work.

I have also tried reading up on concatenating LPCTSTR values. I did find some hits but they seem very complicated and I don't know how to knead them into something for this legacy code.

How can I get dwError to be a part of the log message, preferably in HEX notation.

Upvotes: 0

Views: 459

Answers (1)

Niall
Niall

Reputation: 30605

The question is tagged C++, but the code is and question is written in a C style - the solutions in each vary;

For C++, make use of std::basic_string;

DWORD dwError;
dwError = SomeFunction();

if (dwError)
{
    std::basic_string<TCHAR> msg(_T("Something failed: "));
    msg += std::to_string(dwError);
    Log(msg.c_str());
}

A more C style would be;

DWORD dwError;
dwError = SomeFunction();

if (dwError)
{
    TCHAR buffer[1024] = {};
    _stprintf(buffer, _T("Something failed: %u"), dwError);
    Log(buffer);
}

The documentation for the sprintf links to the format specifiers, and for HEX, it would be %X.

_stprintf(buffer, _T("Something failed: %X"), dwError);

Upvotes: 3

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