I will keep it short and just show you a code example:
class myClass { public: myClass(); int a; int b; int c; } // In the myClass.cpp or whatever m
Just assign to a default-constructed class, like you have. Just use a temporary, though:
struct foo { int a, b, c; foo() : a(), b(), c() {} // use initializer lists }; foo f; f.a = f.b =f.c = 1; f = foo(); // reset