[c++] How to create a template function within a class? (C++)

I know it's possible to make a template function:

template<typename T>
void DoSomeThing(T x){}

and it's possible to make a template class:

template<typename T>
class Object
{
public:
    int x;
};

but is it possible to make a class not within a template, and then make a function in that class a template? Ie:

//I have no idea if this is right, this is just how I think it would look
class Object
{
public:
    template<class T>
    void DoX(){}
};

or something to the extent, where the class is not part of a template, but the function is?

Yes, template member functions are perfectly legal and useful on numerous occasions.

The only caveat is that template member functions cannot be virtual.

See here: Templates, template methods,Member Templates, Member Function Templates

class   Vector
{
  int     array[3];

  template <class TVECTOR2> 
  void  eqAdd(TVECTOR2 v2);
};

template <class TVECTOR2>
void    Vector::eqAdd(TVECTOR2 a2)
{
  for (int i(0); i < 3; ++i) array[i] += a2[i];
}

The easiest way is to put the declaration and definition in the same file, but it may cause over-sized excutable file. E.g.

class Foo
{
public:
template <typename T> void some_method(T t) {//...}
}

Also, it is possible to put template definition in the separate files, i.e. to put them in .cpp and .h files. All you need to do is to explicitly include the template instantiation to the .cpp files. E.g.

// .h file
class Foo
{
public:
template <typename T> void some_method(T t);
}

// .cpp file
//...
template <typename T> void Foo::some_method(T t) 
{//...}
//...

template void Foo::some_method<int>(int);
template void Foo::some_method<double>(double);