STL map类测试

/*
STL map类的使用示例
功能：常用增删改查函数测试
*/

#include <map>
#include <string>
#include <iostream>
using namespace std;

int main()
{
// 无参构造对象
map<char, string> m;
map<int, int> m1;
// 1、常用插入数据的方式
// (1)call insert(ValTy&&) version 
m.insert(make_pair('a', "apple"));
// (2)call insert(const value_type&) version
m1.insert({ { 4, 44 }, { 2, 22 }, { 3, 33 }, { 1, 11 }, { 5, 55 } });
m.insert({ 'b', "balance" });
// (3)使用运算符: 对象名[key] = Value
m['c'] = "clone";

// 2、常用遍历map表方式
// （1）使用迭代器iterator it->first表示key it->second表示value
map<char, string>::iterator it = m.begin();
while (it != m.end())
{
cout << it->first << "<--->" << (it->second).c_str() << endl;
++it;
}
// (2)使用下标遍历
// map < int, CString > 或者 map < int, 结构体名>的元素遍历
int nSize = m1.size();
for(int i = 1; i <= nSize; ++i)
cout << m1[i] << endl;

// 3、 查询表内是否存在指定的key 
// (1)使用find方法
//iterator find(const Key& _Key);
//const_iterator find(const Key& _Key) const;

map<char, string>::iterator m_RcIter = m.find('a');

if (m_RcIter == m.end())
cout << "The map m doesn't have an element "
<< "with a key of 'a'." << endl;
else
cout << "The element of map m with a key of 'a' is: "
<< m_RcIter->second << "." << endl;

m_RcIter = m.find('g');
if (m_RcIter == m.end())
cout << "The map m doesn't have an element "
<< "with a key of 'g'." << endl;
else
cout << "The element of map m with a key of 'g' is: "
<< m_RcIter->second << "." << endl;

// (2)使用 Count方法来查询
//size_type count(const Key& _Key) const;
bool i = m.count('d');
cout << "The number of elements in m1 with a sort key of 'd' is: "
<< i << "." << endl;

// (3)使用at()方法，如果没找到，则中断程序，弹出一个断言
//Type& at(const Key& _Key);
//const Type& at(const Key& _Key) const;
string str1 = m.at('a');

// 4、 删除
//iterator erase(iterator _Where); // 删除指定位置
//iterator erase(iterator _First,iterator _Last); // 删除指定范围
//size_type erase(const key_type& _Key); // 删除指定key
int j = m1.erase(0);
if (j)
cout << "删除成功！" << endl;
else
cout << "删除失败！" << endl;
map<int, int>::iterator m1_it;
m1_it = m1.begin();
m1.erase(m1_it);
m1.erase(m1.begin(), m1.begin()++);

return 0;
}