Question

The following code works fine:

int iLength = SendMessage(hWndEdit, EM_LINELENGTH, 0, 0);
if(iLength > 0) {
    TCHAR* szBuffer = new TCHAR[iLength+1];
    iLength = SendMessage(hWndEdit, EM_GETLINE, 0, (LPARAM)szBuffer);
    szBuffer[iLength] = TEXT('\0');
    MessageBox(hWnd, szBuffer, TEXT("Edit content"), MB_OK);
    delete[] szBuffer;
}

Now I want to do the same thing using std::vector<TCHAR>:

int iLength = SendMessage(hWndEdit, EM_LINELENGTH, 0, 0);
if(iLength > 0) {
    std::vector<TCHAR> data(iLength+1, TEXT('\0'));
    iLength = SendMessage(hWndEdit, EM_GETLINE, 0, (LPARAM)&data[0]);
    MessageBox(hWnd, &data[0], TEXT("Edit content"), MB_OK);
}

It compiles, but at iLength = SendMessage(hWndEdit, EM_GETLINE, 0, (LPARAM)&data[0]); the variable iLength will always be set to 0, and, accordingly, nothing will have been written into my vector.

What is the problem here? Thanks in advance.

Answer 1

From the documentation:

A pointer to the buffer that receives a copy of the line. Before
sending the message, set the first word of this buffer to the size, in
TCHARs, of the buffer.