STL_MAP

// accessing mapped values
#include <iostream>
#include <map>
#include <string>

int main()
{
  std::map<char, std::string> mymap;
  //operator[] 返回指向second的指向的东西
  mymap['a'] = "an element";
  mymap['b'] = "another element";
  mymap['c'] = mymap['b'];

  std::cout << "mymap['a'] is " << mymap['a'] << '\n';
  std::cout << "mymap['b'] is " << mymap['b'] << '\n';
  std::cout << "mymap['c'] is " << mymap['c'] << '\n';
  std::cout << "mymap['d'] is " << mymap['d'] << '\n';

  std::cout << "mymap now contains " << mymap.size() << " elements.\n";
  system("pause");
  return 0;
}

// map::insert (C++98)
#include <iostream>
#include <map>
int main()
{
  std::map<char, int> mymap;
  mymap.insert(std::pair<char, int>('a', 100));//pair使两个值关联起来
  mymap.insert(std::pair<char, int>('z', 200));//pair键值对

  std::pair<std::map<char, int>::iterator, bool> ret;
  ret = mymap.insert(std::pair<char, int>('z', 500));
  if (ret.second == false) {
    std::cout << "element 'z' already existed";
    std::cout << " with a value of " << ret.first->second << '\n';
  }

  // second insert function version (with hint position):
  std::map<char, int>::iterator it = mymap.begin();
  mymap.insert(it, std::pair<char, int>('b', 300));  // max efficiency inserting
  mymap.insert(it, std::pair<char, int>('c', 400));  // no max efficiency inserting

  // third insert function version (range insertion):
  std::map<char, int> anothermap;
  anothermap.insert(mymap.begin(), mymap.find('c'));

  // showing contents:
  std::cout << "mymap contains:\n";
  for (it = mymap.begin(); it != mymap.end(); ++it)
    std::cout << it->first << " => " << it->second << '\n';

  std::cout << "anothermap contains:\n";
  for (it = anothermap.begin(); it != anothermap.end(); ++it)
    std::cout << it->first << " => " << it->second << '\n';
  system("pause");
  return 0;
}

ERASE:

// erasing from map
#include <iostream>
#include <map>

int main()
{
  std::map<char, int> mymap;
  std::map<char, int>::iterator it;

  // 插入数据
  mymap['a'] = 10;
  mymap['b'] = 20;
  mymap['c'] = 30;
  mymap['d'] = 40;
  mymap['e'] = 50;
  mymap['f'] = 60;

  it = mymap.find('b');
  mymap.erase(it);//找到b的迭代器删除

  mymap.erase('c');//通过key值进行删除

  it = mymap.find('e');
  mymap.erase(it, mymap.end()); //删除e到结束的所有
  //打印出所有的元素
  for (it = mymap.begin(); it != mymap.end(); ++it)
    std::cout << it->first << " => " << it->second << '\n';
  system("pause");
  return 0;
}

// map::find
#include <iostream>
#include <map>

int main()
{
  std::map<char, int> mymap;
  std::map<char, int>::iterator it;

  mymap['a'] = 50;
  mymap['b'] = 100;
  mymap['c'] = 150;
  mymap['d'] = 200;

  it = mymap.find('b');//找到b的迭代器
  if (it != mymap.end())//找到后
    mymap.erase(it);//删除
  std::cout << "elements in mymap:" << '\n';
  std::cout << "a => " << mymap.find('a')->second << '\n';
  std::cout << "c => " << mymap.find('c')->second << '\n';
  std::cout << "d => " << mymap.find('d')->second << '\n';
  system("pause");
  return 0;
}