I have only followed antiRTFM tutorials and read 2 books

So, I'll list the things I know better :

basic input output and all the variables : integers ( signed unsigned ), float, double, char arrays if, for, while, switch functions, and passing variables to functions and return type thing classes and the concept of oop with separating declaration and definition in the header and in the source pointers

so this and some more i think is all i know of C++.. But, i need some exercises to test my knowledge because i want to move on to the library SDL, so I don't know if i should feel ready or not to move on to something totally different.. I feel I should know the basics for good at least.

So the question is :

How can i value my c++ knowledge? Is there any online tests? Is there any GDD ( Game Design Document ) for free to use and see if i can manage to do it so "i'd pass" ? ( I'm saying GDD since ill move on to SDL and try to make my own game )

When should I move to SDL? What are ALL the things I should "master" ( master is a big word to say.. but so you understand what i mean ) before moving on ?

Please I'm really in need of expert advice. I think my question is detailed so i hope you understand what i mean and can give me a good reply.

Thanks for the help!