多重映像multimap是一个能包含重复的关键字map
电话号码本，同一个名字可以有很多条目
野生动植物，如需跟踪每一种有斑点的动物出现的时间和地点
可看到很多同一种类的动物
它们在不同的时间和不同的地点出现
如果动物的类型作为关键字 ，需要一个multimap
//: C07:WildLifeMonitor.cpp
// From "Thinking in C++, Volume 2", by Bruce Eckel & Chuck Allison.
// (c) 1995-2004 MindView, Inc. All Rights Reserved.
// See source code use permissions stated in the file 'License.txt',
// distributed with the code package available at www.MindView.net.
#include <algorithm>
#include <cstdlib>
#include <cstddef>
#include <ctime>
#include <iostream>
#include <iterator>
#include <map>
#include <sstream>
#include <string>
#include <vector>
using namespace std;
class DataPoint {
int x, y; // Location coordinates
time_t time; // Time of Sighting
public:
DataPoint() : x(0), y(0), time(0) {}
DataPoint(int xx, int yy, time_t tm) :
x(xx), y(yy), time(tm) {}
// Synthesized operator=, copy-constructor OK
int getX() const { return x; }
int getY() const { return y; }
const time_t* getTime() const { return &time; }
};
string animal[] = {
"chipmunk", "beaver", "marmot", "weasel",
"squirrel", "ptarmigan", "bear", "eagle",
"hawk", "vole", "deer", "otter", "hummingbird",
};
const int ASZ = sizeof animal/sizeof *animal;
vector<string> animals(animal, animal + ASZ);
// All the information is contained in a
// "Sighting," which can be sent to an ostream:
typedef pair<string, DataPoint> Sighting;
ostream&
operator<<(ostream& os, const Sighting& s) {
return os << s.first << " sighted at x= "
<< s.second.getX() << ", y= " << s.second.getY()
<< ", time = " << ctime(s.second.getTime());
}
// A generator for Sightings:
class SightingGen {
vector<string>& animals;
enum { D = 100 };
public:
SightingGen(vector<string>& an) : animals(an) {}
Sighting operator()() {
Sighting result;
int select = rand() % animals.size();
result.first = animals[select];
result.second = DataPoint(
rand() % D, rand() % D, time(0));
return result;
}
};
// Display a menu of animals, allow the user to
// select one, return the index value:
int menu() {
cout << "select an animal or 'q' to quit: ";
for(size_t i = 0; i < animals.size(); i++)
cout <<'['<< i <<']'<< animals[i] << ' ';
cout << endl;
string reply;
cin >> reply;
if(reply.at(0) == 'q') return 0;
istringstream r(reply);
int i;
r >> i; // Converts to int
i %= animals.size();
return i;
}
int main() {
typedef multimap<string, DataPoint> DataMap;
typedef DataMap::iterator DMIter;
DataMap sightings;
srand(time(0)); // Randomize
generate_n(inserter(sightings, sightings.begin()),
50, SightingGen(animals));
// Print everything:
copy(sightings.begin(), sightings.end(),
ostream_iterator<Sighting>(cout, ""));
// Print sightings for selected animal:
for(int count = 1; count < 10; count++) {
// Use menu to get selection:
// int i = menu();
// Generate randomly (for automated testing):
int i = rand() % animals.size();
// Iterators in "range" denote begin, one
// past end of matching range:
pair<DMIter, DMIter> range =
sightings.equal_range(animals[i]);
copy(range.first, range.second,
ostream_iterator<Sighting>(cout, ""));
}
getchar();
} ///:~
输出
bear sighted at x= 74, y= 64, time = Sat Sep 08 18:31:23 2018
bear sighted at x= 91, y= 45, time = Sat Sep 08 18:31:23 2018
bear sighted at x= 24, y= 90, time = Sat Sep 08 18:31:23 2018
bear sighted at x= 11, y= 29, time = Sat Sep 08 18:31:23 2018
bear sighted at x= 70, y= 99, time = Sat Sep 08 18:31:23 2018
bear sighted at x= 91, y= 6, time = Sat Sep 08 18:31:23 2018
beaver sighted at x= 56, y= 82, time = Sat Sep 08 18:31:23 2018
beaver sighted at x= 24, y= 1, time = Sat Sep 08 18:31:23 2018
chipmunk sighted at x= 84, y= 13, time = Sat Sep 08 18:31:23 2018
chipmunk sighted at x= 48, y= 53, time = Sat Sep 08 18:31:23 2018
chipmunk sighted at x= 66, y= 93, time = Sat Sep 08 18:31:23 2018
deer sighted at x= 21, y= 47, time = Sat Sep 08 18:31:23 2018
deer sighted at x= 40, y= 22, time = Sat Sep 08 18:31:23 2018
deer sighted at x= 3, y= 5, time = Sat Sep 08 18:31:23 2018
deer sighted at x= 62, y= 96, time = Sat Sep 08 18:31:23 2018
deer sighted at x= 17, y= 2, time = Sat Sep 08 18:31:23 2018
deer sighted at x= 50, y= 89, time = Sat Sep 08 18:31:23 2018
eagle sighted at x= 74, y= 52, time = Sat Sep 08 18:31:23 2018
eagle sighted at x= 88, y= 42, time = Sat Sep 08 18:31:23 2018
hawk sighted at x= 56, y= 72, time = Sat Sep 08 18:31:23 2018
hawk sighted at x= 21, y= 8, time = Sat Sep 08 18:31:23 2018
marmot sighted at x= 4, y= 48, time = Sat Sep 08 18:31:23 2018
marmot sighted at x= 4, y= 46, time = Sat Sep 08 18:31:23 2018
marmot sighted at x= 13, y= 5, time = Sat Sep 08 18:31:23 2018
marmot sighted at x= 29, y= 41, time = Sat Sep 08 18:31:23 2018
marmot sighted at x= 19, y= 60, time = Sat Sep 08 18:31:23 2018
marmot sighted at x= 86, y= 67, time = Sat Sep 08 18:31:23 2018
marmot sighted at x= 77, y= 33, time = Sat Sep 08 18:31:23 2018
marmot sighted at x= 10, y= 40, time = Sat Sep 08 18:31:23 2018
otter sighted at x= 85, y= 86, time = Sat Sep 08 18:31:23 2018
otter sighted at x= 94, y= 96, time = Sat Sep 08 18:31:23 2018
otter sighted at x= 11, y= 39, time = Sat Sep 08 18:31:23 2018
ptarmigan sighted at x= 58, y= 15, time = Sat Sep 08 18:31:23 2018
ptarmigan sighted at x= 36, y= 85, time = Sat Sep 08 18:31:23 2018
ptarmigan sighted at x= 43, y= 22, time = Sat Sep 08 18:31:23 2018
squirrel sighted at x= 32, y= 10, time = Sat Sep 08 18:31:23 2018
squirrel sighted at x= 42, y= 42, time = Sat Sep 08 18:31:23 2018
squirrel sighted at x= 46, y= 18, time = Sat Sep 08 18:31:23 2018
squirrel sighted at x= 97, y= 42, time = Sat Sep 08 18:31:23 2018
squirrel sighted at x= 58, y= 4, time = Sat Sep 08 18:31:23 2018
squirrel sighted at x= 92, y= 77, time = Sat Sep 08 18:31:23 2018
vole sighted at x= 23, y= 30, time = Sat Sep 08 18:31:23 2018
vole sighted at x= 97, y= 33, time = Sat Sep 08 18:31:23 2018
vole sighted at x= 77, y= 99, time = Sat Sep 08 18:31:23 2018
vole sighted at x= 16, y= 4, time = Sat Sep 08 18:31:23 2018
vole sighted at x= 76, y= 72, time = Sat Sep 08 18:31:23 2018
weasel sighted at x= 16, y= 45, time = Sat Sep 08 18:31:23 2018
weasel sighted at x= 20, y= 0, time = Sat Sep 08 18:31:23 2018
weasel sighted at x= 48, y= 95, time = Sat Sep 08 18:31:23 2018
weasel sighted at x= 85, y= 2, time = Sat Sep 08 18:31:23 2018
ptarmigan sighted at x= 58, y= 15, time = Sat Sep 08 18:31:23 2018
ptarmigan sighted at x= 36, y= 85, time = Sat Sep 08 18:31:23 2018
ptarmigan sighted at x= 43, y= 22, time = Sat Sep 08 18:31:23 2018
weasel sighted at x= 16, y= 45, time = Sat Sep 08 18:31:23 2018
weasel sighted at x= 20, y= 0, time = Sat Sep 08 18:31:23 2018
weasel sighted at x= 48, y= 95, time = Sat Sep 08 18:31:23 2018
weasel sighted at x= 85, y= 2, time = Sat Sep 08 18:31:23 2018
ptarmigan sighted at x= 58, y= 15, time = Sat Sep 08 18:31:23 2018
ptarmigan sighted at x= 36, y= 85, time = Sat Sep 08 18:31:23 2018
ptarmigan sighted at x= 43, y= 22, time = Sat Sep 08 18:31:23 2018
hawk sighted at x= 56, y= 72, time = Sat Sep 08 18:31:23 2018
hawk sighted at x= 21, y= 8, time = Sat Sep 08 18:31:23 2018
squirrel sighted at x= 32, y= 10, time = Sat Sep 08 18:31:23 2018
squirrel sighted at x= 42, y= 42, time = Sat Sep 08 18:31:23 2018
squirrel sighted at x= 46, y= 18, time = Sat Sep 08 18:31:23 2018
squirrel sighted at x= 97, y= 42, time = Sat Sep 08 18:31:23 2018
squirrel sighted at x= 58, y= 4, time = Sat Sep 08 18:31:23 2018
squirrel sighted at x= 92, y= 77, time = Sat Sep 08 18:31:23 2018
weasel sighted at x= 16, y= 45, time = Sat Sep 08 18:31:23 2018
weasel sighted at x= 20, y= 0, time = Sat Sep 08 18:31:23 2018
weasel sighted at x= 48, y= 95, time = Sat Sep 08 18:31:23 2018
weasel sighted at x= 85, y= 2, time = Sat Sep 08 18:31:23 2018
marmot sighted at x= 4, y= 48, time = Sat Sep 08 18:31:23 2018
marmot sighted at x= 4, y= 46, time = Sat Sep 08 18:31:23 2018
marmot sighted at x= 13, y= 5, time = Sat Sep 08 18:31:23 2018
marmot sighted at x= 29, y= 41, time = Sat Sep 08 18:31:23 2018
marmot sighted at x= 19, y= 60, time = Sat Sep 08 18:31:23 2018
marmot sighted at x= 86, y= 67, time = Sat Sep 08 18:31:23 2018
marmot sighted at x= 77, y= 33, time = Sat Sep 08 18:31:23 2018
marmot sighted at x= 10, y= 40, time = Sat Sep 08 18:31:23 2018
将观察到的所有数据都封装到一个DataPoint类中
该类非常简单足以使用综合赋值和拷贝构造函数来对其进行操作
用标准C库时间函数来记录观察的时间