Difference in Data members & Member functions?

 What is the difference b/w data members & member functions?

Data members include members that are declared with any of the fundamental types, as well as other types, including pointer, reference, array types, bit fields, and user-defined types. You can declare a data member the same way as a variable, except that explicit initializers are not allowed inside the class definition. However, a const static data member of integral or enumeration type may have an explicit initializer.

A class X cannot have a member that is of type X, but it can contain pointers to X, references to X, and static objects of X. Member functions of X can take arguments of type X and have a return type of X. For example:

class X
{
      X();
      X *xptr;
      X &xref;
      static X xcount;
      X xfunc(X);
};

Member functions are operators and functions that are declared as members of a class. Member functions do not include operators and functions declared with the friend specifier. These are called friends of a class. You can declare a member function as static; this is called a static member function. A member function that is not declared as static is called a nonstatic member function.

 When the function add() is called in the following example, the data variables a, b, and c can be used in the body of add().

class x
{
public:
      int add()             // inline member function add
      {return a+b+c;};
private:
      int a,b,c;
};