Hmmm. Passwords in executables? Not a good idea indeed. However, if you know a good hashing algorithm, you could calculate a hash value over the password and store this hash value in the executable instead. While a hacker might still get this value from the executable, he will still have to find the proper password that -after hashing- matches this hash value.

Then again, hackers will just modify the code to bypass the whole password checking instead. Again, any security measure that you take to protect your code can be bypassed and probably will be bypassed if it's interesting enough for hackers to do so. All it takes them is some time to crack your code.

Keep in mind that an application doesn't have to be written in C++. There are several other options instead. For example, Delphi, Visual Basic, Fortran to name a few alternative languages. But if you're trying to decompile your own code then you have an advantage since you know which compiler was used.

If you're trying to make decompiling your code a bit more difficult... Well, there are several ways to do so. Tip 1: Don't include debug information in your application.
There are tools like AsPack and AsProtect that will encrypt the executable and thus make it a bit harder to disassemble. Of course there are also tools that can undo these encryption tools again so it's not failsafe.

Still, it does take some skills to disassemble from binary to full sourcecode. And some knowledge of assembly code.