diff --git a/MyTinySTL/deque.h b/MyTinySTL/deque.h
index 7975d83..dc256e9 100644
--- a/MyTinySTL/deque.h
+++ b/MyTinySTL/deque.h
@@ -1245,10 +1245,9 @@ insert_dispatch(iterator position, IIter first, IIter last, input_iterator_tag)
     require_capacity(n, false);
   }
   position = begin_ + elems_before;
-  auto cur = --last;
-  for (size_type i = 0; i < n; ++i, --cur)
+  for (; first != last; ++first, ++position)
   {
-    insert(position, *cur);
+    insert(position, *first);
   }
 }
 
diff --git a/MyTinySTL/iterator.h b/MyTinySTL/iterator.h
index 28a9a69..a3e5cfa 100644
--- a/MyTinySTL/iterator.h
+++ b/MyTinySTL/iterator.h
@@ -103,6 +103,10 @@ struct has_iterator_cat_of
 template <class T, class U>
 struct has_iterator_cat_of<T, U, false> : public m_false_type {};
 
+template <class Iter>
+struct is_exactly_input_iterator : public m_bool_constant<has_iterator_cat_of<Iter, input_iterator_tag>::value && 
+    !has_iterator_cat_of<Iter, forward_iterator_tag>::value> {};
+
 template <class Iter>
 struct is_input_iterator : public has_iterator_cat_of<Iter, input_iterator_tag> {};
 
diff --git a/MyTinySTL/stream_iterator.h b/MyTinySTL/stream_iterator.h
new file mode 100644
index 0000000..0da2140
--- /dev/null
+++ b/MyTinySTL/stream_iterator.h
@@ -0,0 +1,80 @@
+#ifndef MYTINYSTL_STREAM_ITERATOR_H_
+#define MYTINYSTL_STREAM_ITERATOR_H_
+
+#include "basic_string.h"
+
+namespace mystl
+{
+
+template<typename T, typename CharT = char,
+        typename Traits = std::char_traits<CharT>, typename Dist = ptrdiff_t>
+class istream_iterator
+: public iterator<input_iterator_tag, T, Dist, const T*, const T&>
+{
+public:
+    using char_type = CharT;
+    using traits_type = Traits;
+    using istream_type = std::basic_istream<CharT, Traits>;  
+
+    istream_iterator() /* noexcept(std::is_nothrow_default_constructible<T>::value) */
+        : m_stream{nullptr}, m_value{} {}
+
+    istream_iterator(istream_type& is)
+        : m_stream{std::addressof(is)}
+    { read(); }
+
+    istream_iterator(const istream_iterator& other) /* noexcept(std::is_nothrow_copy_constructible<T>::value) */
+        = default;   // memberwise copy
+
+    istream_iterator& operator=(const istream_iterator&) = default;   // memberwise copy-asgn
+
+    ~istream_iterator() = default;
+
+    const T& operator*() const noexcept {
+        MYSTL_DEBUG(m_stream != nullptr);
+        return m_value;
+    }
+
+    const T* operator->() const noexcept {
+        return std::addressof(*this);
+    }
+
+    istream_iterator& operator++() {
+        MYSTL_DEBUG(m_stream != nullptr);
+        read();
+        return *this;
+    }
+
+     istream_iterator operator++(int) {
+        auto tmp = *this;
+        ++*this;
+        return tmp;
+    }
+
+private:
+    istream_type* m_stream;
+    T m_value; 
+
+    void read() {
+        if (m_stream && !(*m_stream >> m_value)) {  // m_stream 有效且读到 EOS
+            m_stream = nullptr;  
+        }
+    }  
+
+    friend bool operator==(const istream_iterator& lhs, const istream_iterator& rhs) {
+        return lhs.m_stream == rhs.m_stream;
+    }  
+
+    friend bool operator!=(const istream_iterator& lhs, const istream_iterator& rhs) {
+        return lhs.m_stream != rhs.m_stream;
+    }  
+};
+
+
+// TODO 
+// template<typename T, typename CharT = char,
+//          typename Traits = char_traits<CharT> >
+// class ostream_iterator : public iterator<output_iterator_tag, void, void, void, void> {};
+}
+
+#endif
\ No newline at end of file
diff --git a/Test/vector_test.h b/Test/vector_test.h
index 8b79ef6..e230203 100644
--- a/Test/vector_test.h
+++ b/Test/vector_test.h
@@ -7,6 +7,10 @@
 
 #include "../MyTinySTL/vector.h"
 #include "test.h"
+#include "../MyTinySTL/stream_iterator.h"
+#include <iostream>
+#include <iterator>
+#include <sstream>
 
 namespace mystl
 {
@@ -33,7 +37,19 @@ void vector_test()
   v9 = std::move(v3);
   v10 = { 1,2,3,4,5,6,7,8,9 };
 
-  FUN_AFTER(v1, v1.assign(8, 8));
+  //输入迭代器测试
+  std::istringstream inputStream("6 2 3 4 5 5 7");
+  mystl::istream_iterator<int> beg(inputStream), end;
+  mystl::vector<int> v11({9,8,7,6,5,4});
+  v11.assign(beg, end);
+  int count = 0;
+  for(beg; beg!=end; ++beg)
+    std::cout<<*beg;
+  std::cout << std::endl;
+  std::cout << *beg << std::endl;
+  std::cout << *beg << std::endl;
+  COUT(v11);
+  
   FUN_AFTER(v1, v1.assign(a, a + 5));
   FUN_AFTER(v1, v1.emplace(v1.begin(), 0));
   FUN_AFTER(v1, v1.emplace_back(6));