list0717.cpp

teach yourself C++ in 21 days 第五版

//Listing 7.17
//Using a forever loop to manage user interaction
#include <iostream>

// prototypes
int menu();
void DoTaskOne();
void DoTaskMany(int);

using namespace std;

int main()
{
   bool exit = false;
   for (;;)
   {
      int choice = menu();
      switch(choice)
      {
        case (1):
            DoTaskOne();
            break;
        case (2):
            DoTaskMany(2);
            break;
        case (3):
            DoTaskMany(3);
            break;
        case (4):
            continue;  // redundant!
            break;
        case (5):
            exit=true;
            break;
        default:
            cout << "Please select again! " << endl;
            break;
      }             // end switch

      if (exit == true)
         break;
   }                // end forever
   return 0;
}                   // end main()

int menu()
{
   int choice;

   cout << " **** Menu **** "   << endl << endl;
   cout << "(1) Choice one. "   << endl;
   cout << "(2) Choice two. "   << endl;
   cout << "(3) Choice three. " << endl;
   cout << "(4) Redisplay menu. " << endl;
   cout << "(5) Quit. "    << endl << endl;
   cout << ": ";
   cin >> choice;
   return choice;
}

void DoTaskOne()
{
   cout << "Task One! " << endl;
}

void DoTaskMany(int which)
{
   if (which == 2)
      cout << "Task Two! " << endl;
   else
      cout << "Task Three! " << endl;
}