How can I read and write text files using the windows api - c++

Question

There are many similar questions, but mine is a bit different. Mine involves a Windows GUI. I am using an open file dialog or an "OPENFILENAME". I want to get the dialog result as OK when the user clicks the OK button and then open a text encoded file. I have done it in Java, but the UI looks weird. So I am not sure whether or not people would like it. I want to learn C++ as well, so I need some help. I have a text box called "hWndEdit" in the WM_COMMAND message inside my program. After opening, the text in the file is supposed to be displayed in the textBox I have specified. I have defined the function in a header file with the following code:
#include <iostream>
#include <fstream>
#include <windows.h>
using namespace std;
void OpenFile()
{
OPENFILENAME ofn; // common dialog box structure
HWND hwnd = nullptr; // owner window
HANDLE hf; // file handle
// Initialize OPENFILENAME
ZeroMemory(&ofn, sizeof(ofn));
ofn.lStructSize = sizeof(ofn);
ofn.hwndOwner = hwnd;
// Set lpstrFile[0] to '\0' so that GetOpenFileName does not
// use the contents of szFile to initialize itself.
ofn.nMaxFile = sizeof(szFile);
ofn.lpstrFilter = L"NoteRecorder Notes\0(*.recnote)\0Text\0(*.txt)\0";
ofn.nFilterIndex = 1;
ofn.lpstrFileTitle = NULL;
ofn.nMaxFileTitle = 0;
ofn.lpstrInitialDir = NULL;
ofn.Flags = OFN_PATHMUSTEXIST | OFN_FILEMUSTEXIST;
// Display the Open dialog box.
if (GetOpenFileName(&ofn) == TRUE)
{
hf = CreateFile(ofn.lpstrFile,
GENERIC_READ,
0,
(LPSECURITY_ATTRIBUTES)NULL,
OPEN_EXISTING,
FILE_ATTRIBUTE_NORMAL,
(HANDLE)NULL);
}
}
Then I call it from my WM_COMMAND message:
case WM_COMMAND:
switch (wParam)
{
case 12:
OpenFile();
break;
}
But when the user presses the OK button in the OPENFILENAME, it doesn't read any text from the file. How can I accomplish this?
And I want to write files with a save file dialog. Tell me how to do that as well.

Answer 1

The main purpose of the functions GetOpenFileName and GetSaveFileName is to provide you with the filename that the user selected. However, doing the actual File Input and Output is a different issue. You can use the standard C/C++ library for that or you can use the Windows API functions, such as CreateFile, ReadFile and WriteFile.
Since you seem to already be using the function CreateFile, it would make sense to call ReadFile after verifying that the function call to CreateFile succeeded (i.e. that it did not return INVALID_HANDLE_VALUE). After reading the data, you can add a terminating null character to the data (you should make sure that the memory buffer is large enough) and then pass it to the SetDlgItemText function (if the text box is in a dialog box) or SetWindowText function.