Cheat Engine

[hhhuut]

Is that really all of your source code?

[hhhuut]

Well, let's start with the core, the "WriteProcessMemory" function, which is a function from the windows API and can't be called without arguments: https://msdn.microsoft.com/de-de/library/windows/desktop/ms681674(v=vs.85).aspx

[atom0s]

You don't seem to understand what you are doing at all. You should stop and actually learn what you are doing and learn the language you are coding in rather than get spoonfed things you don't understand in general. It will just lead to you posting more questions because you are unfamiliar with what you are doing.

[hhhuut]

Well, I can give you some pseudo-code to get the order in which to do things, but as atom0s said, you need to understand what you're doing.

1) Obtain a handle to the target process (using OpenProcess)
2) Get your desired address (if it's static, better use the module+offset combo instead of an absolute hex address, else follow a pointer or something)
3) Call the WriteProcessMemory function with all the arguments and also pay attention to the value size (because if the value you want to change is a 0/1 byte flag, then you don't want to write the whole integer size of 4 bytes)
4) Close the handle to the target process

In addition, I'd always recommend to do some basic exception handling, so i.e. analyze the function results, do some basic checks yourself (address=0), use try-except/finally blocks, etc.

Fun fact: All the above doesn't even require you to inject a complete dll into other processes.