usingtypedef.cpp

24学时攻克C++光盘源代码 深入浅出 方便实用

 // Listing 20.8. using typedef 
 #include <iostream>
 using namespace std; // this file uses std:: objects
 
 void Square (int&,int&);
 void Cube (int&, int&);
 void Swap (int&, int &);
 void GetVals(int&, int&);
 typedef  void (*VPF) (int&, int&) ;
 void PrintVals(VPF,int&, int&);
 
 int main()
 {
     int valOne=1, valTwo=2;
     int choice;
     bool fQuit = false;
 
     VPF pFunc;
 
     while (fQuit == false)
     {
         cout << "(0)Quit (1)Change Values"
             << "(2)Square (3)Cube (4)Swap: ";
         cin >> choice;
         switch (choice)
         {
         case 1:
             pFunc = GetVals;
             break;
         case 2:
             pFunc = Square;
             break;
         case 3:
             pFunc = Cube;
             break;
         case 4:
             pFunc = Swap;
             break;
         default:
             fQuit = true;
             break;
         }
         if (fQuit == true)
             break;
         PrintVals ( pFunc, valOne, valTwo);
     }
     return 0;
 }
 
 void PrintVals( VPF pFunc,int& x, int& y)
 {
     cout << "x: " << x << " y: " << y << endl;
     pFunc(x,y);
     cout << "x: " << x << " y: " << y << endl;
 }
 
 void Square (int & rX, int & rY)
 {
     rX *= rX;
     rY *= rY;
 }
 
 void Cube (int & rX, int & rY)
 {
     int tmp;
 
     tmp = rX;
     rX *= rX;
     rX = rX * tmp;
 
     tmp = rY;
     rY *= rY;
     rY = rY * tmp;
 }
 
 void Swap(int & rX, int & rY)
 {
     int temp;
     temp = rX;
     rX = rY;
     rY = temp;
 }
 
 void GetVals (int & rValOne, int & rValTwo)
 {
     cout << "New value for ValOne: ";
     cin >> rValOne;
     cout << "New value for ValTwo: ";
     cin >> rValTwo;
 }