Passing, AND modifying object values (passing const... discards qualifiers error)

So I am trying to pass an object to a function and access its methods, some of which modify its values. However, I haven't done this before, and I was following this example

Use & to get object address : object pointer « Class « C++ Tutorial

but since I keep getting

passing `...' as `this' argument of `...' discards qualifiers

I realize I am not supposed to be using "const", since that Object is not remaining constant. (vs, the example where they dont actually change the values)

What should a function be, which is receiving an object in order to be modified

If any examples could be provided or a link to another tutorial, that would help me out A LOT, thanks

What exactly is the code that you tried?

Code:

---

const Target *  const animateTarget( const Target *  const tar){

...
tar->setValue(something)
....
}

---

Well, the code example in the tutorial that you linked to compiles for me without even a warning. So, you should post the smallest and simplest example that demonstrates the problem, not a fragment that could be correct, or could be wrong, depending on what you don't show.

Quite obviously you shouldn't insist that the object is const if you want to modify it (by calling non-const methods).

Code:

---

const Target *  const animateTarget( Target *  const tar){
    ...
    tar->setValue(something)
    ....
}

---

If the intention was really not to modify it, then you shouldn't be calling setValue() (or that method should be marked "const", which is hard to believe it is).

@laserlight: I don't believe for one second you didn't immediately know what the problem was.
Actually, I usually refuse to answer badly formulated questions as well, but I consider this one to be okay. I mean, even from his first post you can easily tell he tried to call a non-const function on a const object.

Pointing out what the problem is as opposed to where the problem is sometimes just isn't helpful.
Pointing out where and why is even more helpful.