map<int, float> test_map;

test_map[1] = 1.0;

test_map[3] = 3.0;

test_map[7] = 7.0;

test_map[2] = 2.0;

test_map[10] = 10.0;

test_map[8] = 8.0;

test_map[22] = 22.0;

test_map[15] = 15.0;

test_map[13] = 11.0;

cout << test_map.size() << endl;

//从输出可以看出，map 迭代器是按照 key 值从小到大依次访问其中的元素的

for(map<int, float>::iterator it = test_map.begin(), itend = test_map.end();it!=itend;it++) {

cout << "key: " << it->first << " value: " << it->second << endl;

}

map<int, float> test_map_;

test_map_[5] = 1.0;

test_map_[9] = 3.0;

test_map_[12] = 7.0;

test_map_[2] = 2.0;

test_map_[10] = 10.0;

test_map_[13] = 8.0;

test_map_[8] = 22.0;

test_map_[15] = 15.0;

cout << test_map_.size() << endl;

for(map<int, float>::iterator it = test_map_.begin(), itend = test_map_.end();it!=itend;it++) {

cout << "key: " << it->first << " value: " << it->second << endl;

}

map<int, float>::iterator it1 = test_map.begin();

map<int, float>::iterator it2 = test_map_.begin();

map<int, float>::iterator it1end = test_map.end();

map<int, float>::iterator it2end = test_map_.end();

vector<pair<int, int> > process;

typedef pair<int, int> make_pair;

process.push_back(make_pair(it1->first, it2->first));

//这段程序的作用是寻找出两个 map 结构中 key 相等的元素

while(it1!=it1end && it2!=it2end) {

if(it1->first == it2->first)

{

cout << "the same key" << it1->first << endl;

it1++;

it2++;

process.push_back(make_pair(it1->first, it2->first));

}

else if(it1->first < it2->first)

{

//返回一个不小于it2-first的迭代器指针

it1 = test_map.lower_bound(it2->first);

process.push_back(make_pair(it1->first, it2->first));

}

else

{

it2 = test_map_.lower_bound(it1->first);

process.push_back(make_pair(it1->first, it2->first));

}

}

//结束while循环时，有一个指向end，所以最后一组 push_back 的是越界的数据

process.pop_back();

vector<make_pair>::iterator it = process.begin(), itend = process.end();

while(it!=itend) {

cout << it->first << ' ' << it->second << endl;

it++;

}

return 0;