C++ 模板套模板

1.模板类中有成员是模板

#include <iostream>
#include <typeinfo>
using namespace std;

template<class T>
class Outer 
{
public:
  template<class R>
  class Inner 
  {
  public:
    void f();
  };
};

template<class T> 
template <class R>
void Outer<T>::Inner<R>::f()
{
  cout << "Outer == " << typeid(T).name() << endl;
  cout << "Inner == " << typeid(R).name() << endl;
  cout << "Full Inner == " << typeid(*this).name() << endl;
}

int main() 
{
  Outer<int>::Inner<bool> inner;
  inner.f();
} /**////:~

//output:
//Outer == int
//Inner == bool
//Full Inner == class Outer<int>::Inner<bool>
//Press any key to continue . . .

　　2、模板类参数是模板

// A print function for standard C++ sequences
#include <iostream>
#include <list>
#include <memory>
#include <vector>
#include <deque>
using namespace std;

template<class T, template<class U, class = allocator<U> >
                  class Seq>
void printSeq(Seq<T>& seq) 
{
  for (typename Seq<T>::iterator b = seq.begin();
       b != seq.end();)
    cout << *b++ << endl;
}

int main() 
{
  // Process a vector
  vector<int> v;
  v.push_back(1);
  v.push_back(2);
  printSeq(v);
  // Process a list
  list<int> lst;
  lst.push_back(3);
  lst.push_back(4);
  printSeq(lst);

  // Process a deque
  deque<int> d;
  d.push_back(5);
  d.push_back(6);
  printSeq(d);
} /**////:~

　　注意：typename 通知编译器被限定的标识符应该为类型，不同与typedef 是定义新的类型。

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