calcinventory.cpp

Think in C++ 第二版源码

//: C21:CalcInventory.cpp
// From Thinking in C++, 2nd Edition
// Available at http://www.BruceEckel.com
// (c) Bruce Eckel 1999
// Copyright notice in Copyright.txt
// More use of for_each()
#include "Inventory.h"
#include "PrintSequence.h"
#include <vector>
#include <algorithm>
using namespace std;

// To calculate inventory totals:
class InvAccum {
  int quantity;
  int value;
public:
  InvAccum() : quantity(0), value(0) {}
  void operator()(const Inventory& inv) {
    quantity += inv.getQuantity();
    value += inv.getQuantity() * inv.getValue();
  }
  friend ostream& 
  operator<<(ostream& os, const InvAccum& ia) {
    return os << "total quantity: " 
      << ia.quantity
      << ", total value: " << ia.value;
  }
};

int main() {
  vector<Inventory> vi;
  generate_n(back_inserter(vi), 15, InvenGen());
  print(vi, "vi");
  InvAccum ia = for_each(vi.begin(),vi.end(),
    InvAccum());
  cout << ia << endl;
} ///:~