ok, more specifically: using the C++ language itself and not using a language instead which was written in C++. (i.e. if i had an assignment for assembly, i wouldnt be able to (restricted by the assignment/professor) write it in C++, right?)
by restricted i figured that this is an assignment (school or work) and the requirement is "[...] must be written in C++" or whatever. of course if its a personal project or assignment without this restriction, then he could write it in assembly if he wanted.
but yes, it is a good point to note that C++ is often used to create a new language.