hour20_2.cpp

《24学时精通c++》的随书源码的下半部分。欢迎下载学习。

 // Listing 20.6 arrays of pointers to functions
 #include <iostream>
 
 void Square (int&,int&);
 void Cube (int&, int&);
 void Swap (int&, int &);
 void GetVals(int&, int&);
 void PrintVals(int, int);
 
 int main()
 {
     int valOne=1, valTwo=2;
     int choice,i;
     const int MaxArray = 5;
     void (*pFuncArray[MaxArray])(int&, int&);
 
     for (i=0;i<MaxArray;i++)
     {
         std::cout << "(1)Change Values "
             << "(2)Square (3)Cube (4)Swap: ";
         std::cin >> choice;
         switch (choice)
         {
         case 1:
             pFuncArray[i] = GetVals; 
             break;
         case 2:
             pFuncArray[i] = Square; 
             break;
         case 3:
             pFuncArray[i] = Cube; 
             break;
         case 4:
             pFuncArray[i] = Swap; 
             break;
         default:
             pFuncArray[i] = 0;
         }
     }
 
     for (i=0;i<MaxArray; i++)
     {
         if (pFuncArray[i] != 0)     // This added checking will skip any entries with an invalid 
         {                           // menu selection (bullet proofing the run).
            pFuncArray[i](valOne,valTwo);
            PrintVals(valOne,valTwo);
         }
     }
     return 0;
 }
 
 void PrintVals(int x, int y)
 {
     std::cout << "x: " << x << " y: " << y << std::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)
 {
     std::cout << "New value for ValOne: ";
     std::cin >> rValOne;
     std::cout << "New value for ValTwo: ";
     std::cin >> rValTwo;
 }