Add an ostream parameter

ch16/ex16.19.20/main.cpp

@@ -22,44 +22,41 @@
 
 //! ex16.19
 template<typename Container>
-std::ostream& print(Container& c);
+std::ostream& print(Container& c, std::ostream &os);
 
 //! ex16.20
 template<typename Container>
-std::ostream& print2(Container& c);
+std::ostream& print2(Container& c, std::ostream &os);
 
 int main()
 {
     std::vector<int> v = {1,23,6,4,5,7,4};
     std::list<std::string> l = {"ss","sszz","saaas","s333s","ss2","sss"};
-    print2(v);
-    print2(l);
-
-
-
+    print2(v, std::cout);
+    print2(l, std::cout);
 
     return 0;
 }
 
 //! ex16.19 using size() to control the loop
 template<typename Container>
-std::ostream & print(Container &c)
+std::ostream & print(Container &c, std::ostream &os)
 {
     typedef typename Container::size_type size_type;
 
     auto it = c.begin();
     for(size_type i = 0; i!= c.size(); ++i)
-        std::cout << *it++ << "\n";
+        os << *it++ << "\n";
 
-    return std::cout;
+    return os;
 }
 
 //! ex16.20 using iterator to control the loop
 template<typename Container>
-std::ostream& print2(Container& c)
+std::ostream& print2(Container& c, std::ostream &os)
 {
     for (auto it = c.begin(); it != c.end(); ++it)
-        std::cout << *it << "\n";
+        os << *it << "\n";
 
-    return std::cout;
+    return os;
 }