speciallist.cpp

c++设计思想

//: C08:SpecialList.cpp
// From "Thinking in C++, 2nd Edition, Volume 2"
// by Bruce Eckel & Chuck Allison, (c) 2001 MindView, Inc.
// Available at www.BruceEckel.com.
// Using the second version of transform()
//{L} ../TestSuite/Test
//{-g++295}
//{-msc}
#include "Inventory.h"
#include "PrintSequence.h"
#include <vector>
#include <algorithm>
#include <cstdlib>
#include <ctime>
using namespace std;

struct Discounter {
  Inventory operator()(const Inventory& inv,
    float discount) {
    return Inventory(inv.getItem(), 
      inv.getQuantity(), 
      inv.getValue() * (1 - discount));
  }
};

struct DiscGen {
  DiscGen() { srand(time(0)); }
  float operator()() {
    float r = float(rand() % 10);
    return r / 100.0;
  }
};

int main() {
  vector<Inventory> vi;
  generate_n(back_inserter(vi), 15, InvenGen());
  print(vi, "vi");
  vector<float> disc;
  generate_n(back_inserter(disc), 15, DiscGen());
  print(disc, "Discounts:");
  vector<Inventory> discounted;
  transform(vi.begin(),vi.end(), disc.begin(), 
    back_inserter(discounted), Discounter());
  print(discounted, "discounted");
} ///:~