Update ex6_54_55_56.cpp

ch06/ex6_54_55_56.cpp

@@ -1,4 +1,4 @@
-//! @Alan
+//! @Yue Wang
 //!
 //! Exercise 6.54:
 //! Write a declaration for a function that takes two int
@@ -17,9 +17,7 @@
 #include <iostream>
 #include <string>
 #include <vector>
-#include <iterator>
-
-using namespace std;
+using std::vector; using std::cout;
 
 //!
 //! @brief Exercise 6.54
@@ -32,25 +30,21 @@ typedef decltype(f) fp;//fp is just a function type not a function pointer
 //! @brief Exercise 6.55
 //! @note  Store pointers to these functions in the vector
 //!
-inline int NumAdd(const int n1, const int n2)  {return n1+n2;}
-inline int NumSub(const int n1, const int n2)  {return n1-n2;}
-inline int NumMul(const int n1, const int n2)  {return n1*n2;}
-inline int NumDiv(const int n1, const int n2)  {return n1/n2;}
-
-vector<fp*> v{NumAdd, NumSub, NumMul, NumDiv};
+inline int NumAdd(const int n1, const int n2)  { return n1 + n2; }
+inline int NumSub(const int n1, const int n2)  { return n1 - n2; }
+inline int NumMul(const int n1, const int n2)  { return n1 * n2; }
+inline int NumDiv(const int n1, const int n2)  { return n1 / n2; }
 
+vector<fp*> v{ NumAdd, NumSub, NumMul, NumDiv };
 
 int main()
 {
     //!
     //! @brief Exercise 6.56
     //! @note  Call each element in the vector and print their result.
     //!
-    for(vector<fp*>::iterator it = v.begin(); it != v.end(); ++it)
-    {
-        cout << (*it)(2,2)  // here shows how to use it!
-                << std::endl;
-    }
+    for (auto it = v.cbegin(); it != v.cend(); ++it)
+        cout << (*it)(2, 2) << std::endl;
 
+    return 0;
 }
-