Clear all values? It is rather easy, just set them all to zero... Or better yet, set them to a number generated by a random number generator to really throw off people.

Seriously, if you are going to go to the trouble to write all of the values to disk, what is just an additional line setting the value to zero, or some other randomly generated value?

I have not used memory trainers myself but i guess they work by checking the memory for certain values (which the user identifies in game) until they find the variable memory locations. Then, when the memory locations are found they let the user change those values at the located addresses. Or are they more sophisticated?

If not, why don't you try out a couple of ways yourself and see if you can fool (most of) them.

Suggestion1:
For example you could try storing each variable in another form (using the binary operator XOR for example to invert it, it is pretty fast). Or using something like x = x + 123 % sizeof(x). As the value will be changed it might be harder to look up.

Suggestion2:
You could try storing each variable in multiple locations (L1, L2, ... , Ln). WRITEing first checks that L1 ... Ln are all equal, if not someone has cheated. And then writes the same value to all locations. When READing you read from an arbitrary location Lx where 1 <= x <= n. Even if they can look up all locations they need to change them all, and all before you do your next WRITE or the cheating will be detected.

Suggestion3:
Suggestion1 && Suggestion2

Just some ideas, the above will slow down your program to a certain extent. But i wonder if it will ever be noticable (read as: i think not).

I agree. I have never understood why to cheat in a game anyway? It spoils your own fun. It must be some 1337 thingy that passed me by.