嵌入式C++（十二）

key可以重复

案例：
公司：
销售部：2名
技术研发部：1名
财务部：4名
人员信息：姓名，年龄，电话，工资等组成
通过multimap进行信息的插入，保存，显示
分部门显示员工信息

#include <iostream>
#include <string>
#include <algorithm>
#include <map>
using namespace std;
class Employee
{
private:
  int id;
  string name;
public:
  Employee(int i, string n)
  {
  id = i;
  name = n;
  }
  void show()
  {
  cout << "工号：" << id << "姓名："<<name<<endl;
  }
};
int main(void)
{
  Employee e1(1000,"aa");
  Employee e2(1001, "bb");
  Employee e3(1002, "cc");
  Employee e4(1003, "dd");
  Employee e5(1004, "ee");
  Employee e6(1005, "ff");
  Employee e7(1006, "gg");
  Employee e8(1007, "ll");
  multimap<string, Employee> m;
  //销售部有2名员工
  m.emplace(make_pair("sale", e1));
  m.emplace(make_pair("sale", e2));
  //研发部有两名员工
  m.emplace(make_pair("development", e3));
  m.emplace(make_pair("development", e8));
  //财务部有四名员工
  m.emplace(make_pair("finance",e4));
  m.emplace(make_pair("finance", e5));
  m.emplace(make_pair("finance", e6));
  m.emplace(make_pair("finance", e7));
  cout << m.count("Finance") << endl;
  for (auto it = m.begin(); it != m.end(); it++)
  {
  cout << "部门：" << it->first << endl;
  it->second.show();
  }
  return 0;
}

双端数组，接口和vector类似，在头部和尾部非常迅速，但是在中部添加元素比较费时，需要添加头文件#include

#include <iostream>
#include <string>
#include <deque>
using namespace std;
int main(void)
{
  int data[5] = { 1,2,3,4,5 };
  deque<int> d1;
  deque<int> d2(data, data + 5);
  deque<int> d3(10,1);
  for (auto &d : d2)
  {
  cout << d << " ";
  }
  cout << endl;
  d2.emplace_back(6);
  d2.emplace_front(0);
  for (auto &d : d2)
  {
  cout << d << " ";
  }
  cout << endl;
  d2.pop_back();
  d2.pop_front();
  d2.front() = 10000;
  d2.back() = 20000;
  for (auto &d : d2)
  {
  cout << d << " ";
  }
  cout << endl;
  return 0;
}

stack（LIFO）
queue(fifo)
priority_queue()

#include <stack>
#include <iostream>
#include <time.h>
using namespace std;
int main(void)
{
  stack<int> s;
  srand(time(NULL));
  int num;
  for (int i = 0; i < 10; i++)
  {
  num = rand() % 10;
  s.push(num);
  cout << num << "进栈成功" << endl;
  }
  cout << "栈顶元素是：" << s.top() << endl;
  cout << "栈的大小：" << s.size() << endl;
  //栈和队列不存在遍历，不存在迭代器
  while (!s.empty())
  {
  cout << s.top() << "出栈" << endl;
  s.pop();
  }
  s.pop();
  return 0;
}

#include <queue>
#include <iostream>
#include <time.h>
using namespace std;
int main(void)
{
  queue<int> q;
  for (int i = 0; i < 10; i++)
  {
  q.push(i);
  cout << i << " 进队成功" << endl;
  }
  cout << "队头元素：" << q.front() << endl;
  cout << "队尾元素：" << q.back() << endl;
  cout << "队列大小：" <<q.size()<< endl;
  while (!q.empty())
  {
  cout << q.front() << "出队" << endl;
  q.pop();
  }
  return 0;
}

#include <queue>
#include <iostream>
#include <time.h>
using namespace std;
int main(void)
{
  //priority_queue<int> p;
  //priority_queue<int, vector<int>, less<int>> p;  //等价于priority_queue<int> p;
  priority_queue<int, deque<int>, greater<int>> p;
  srand(time(NULL));
  int num;
  for (int i = 0; i < 10; i++)
  {
  num = rand() % 10;
  p.emplace(num);
  cout << num << "进队成功" << endl;
  }
  cout << "队头元素 " << p.top() << endl;
  cout << "队列长度：" << p.size() << endl;
  while (!p.empty())
  {
  cout << p.top() <<"出队"<<endl;
  p.pop();
  }
  return 0;
}

异常处理就是处理程序中错误，所谓错误就是程序运行时发生的一些异常事件（栈溢出，数组下标越界等）

分为三个部分：
抛出异常：throw
检测异常：
try
{
    可能发生异常的语句
}
捕获异常: 
catch(异常类型 变量名)
{
    异常处理语句
}
抛出异常：throw关键字，当执行throw之后，try语句块就会立即结束，运行catch中的异常处理的语句。
 throw 表达式、常量、变量
 throw的用法和惹他于任内类似，throw是抛出一个值，return是上一级调用的函数

#include <iostream>
using namespace std;
int Div(int x, int y)
{
  if (0 == y)
  {
  //return -1;
  //throw 0;  //抛出异常
  throw 'a';
  }
  return x / y;
}
int main(void)
{
  int a, b;
  cin >> a >> b;
  try   //把可能出现异常的代码放在try语句中
  {
  cout << Div(a, b) << endl;
  cout << "hello world" << endl;
  }
  catch(int)
  {
  cout << "zero exception" << endl;
  }
  catch (char)
  {
  cout << "char exception" << endl;
  }
  cout << "nihao nanjing" << endl;
  return 0;
}

#include <iostream>
using namespace std;
//int Div(int x, int y);  //可能抛出任何异常
//int Div(int x, int y) throw(int, char);  //只能抛出int,char类型的异常
int Div(int x, int y) throw();  //不允许抛出任何异常
int main(void)
{
  int a, b;
  cin >> a >> b;
  try   //把可能出现异常的代码放在try语句中
  {
  cout << Div(a, b) << endl;
  cout << "hello world" << endl;
  }
  catch(int)
  {
  cout << "zero exception" << endl;
  }
  catch (char)
  {
  cout << "char exception" << endl;
  }
  catch (double)
  {
  cout << "double exception" << endl;
  }
  cout << "nihao nanjing" << endl;
  return 0;
}
int Div(int x, int y) throw()
{
  if (0 == y)
  {
  //return -1;
  //throw 0;  //抛出异常
  //throw 'a';
  throw 3.14;
  }
  return x / y;
}

#include <iostream>
using namespace std;
int Div(int x, int y);  //可能抛出任何异常
//int Div(int x, int y) throw(int, char);  //只能抛出int,char类型的异常
//int Div(int x, int y) throw();  //不允许抛出任何异常
class Test
{
public:
  Test()
  {
  cout << "Test的构造函数" << endl;
  }
  Test(const Test &obj)
  {
  cout << "Test的拷贝构造" << endl;
  }
  void print()
  {
  cout << "Test exception" << endl;
  }
  ~Test()
  {
  cout << "Test的析构函数" << endl;
  }
};
int main(void)
{
  int a, b;
  cin >> a >> b;
  try   //把可能出现异常的代码放在try语句中
  {
  cout << Div(a, b) << endl;
  cout << "hello world" << endl;
  }
  catch(int)
  {
  cout << "zero exception" << endl;
  }
  catch (char)
  {
  cout << "char exception" << endl;
  }
  catch (double)
  {
  cout << "double exception" << endl;
  }
  /*catch (Test t) //调用拷贝构造函数
  {
  t.print();
  }*/
  /*catch (Test &t)  //推荐
  {
  t.print();
  }*/
  catch (Test *t)
  {
  t->print();
  delete t;  //需要手动释放
  }
  cout << "nihao nanjing" << endl;
  return 0;
}
int Div(int x, int y)
{
  if (0 == y)
  {
  //return -1;
  //throw 0;  //抛出异常
  //throw 'a';
  //throw 3.14;
  //throw Test();
  throw new Test();
  }
  return x / y;
}

#include <iostream>
#include <exception>
using namespace std;
int Div(int x, int y);  //可能抛出任何异常
//int Div(int x, int y) throw(int, char);  //只能抛出int,char类型的异常
//int Div(int x, int y) throw();  //不允许抛出任何异常
class Exception :public exception
{
private:
  string Errmsg;
public:
  Exception(string e) :Errmsg(e)
  {
  }
  virtual const char* what() const throw()  //虚函数重写
  {
  return Errmsg.data();
  }
};
int main(void)
{
  int a, b;
  cin >> a >> b;
  try
  {
  cout << Div(a,b) << endl;
  }
  catch (const std::exception &e)
  {
  cout << e.what() << endl;
  }
  return 0;
}
int Div(int x, int y)
{
  if (0 == y)
  {
  //return -1;
  //throw 0;  //抛出异常
  //throw 'a';
  //throw 3.14;
  //throw Test();
  throw Exception("除数不能为0");
  throw bad_alloc();
  }
  return x / y;
}

优点:
1.pop()-->返回下一个元素
2.如果stack为空，pop和top会抛出异常

#include <iostream>
#include <exception>
#include <deque>
using namespace std;
template <typename T>
class Stack
{
protected:
  std::deque<T> c;
public:
  class ReadEmptyStack :public exception
  {
  public:
  virtual const char* what() const throw()
  {
    return "read empty stack";
  }
  };
  //typename std::deque<T>::size_type size() const //类型依赖于模板参数的限定名，前面必须加typename
  auto size() const
  {
  return c.size();
  }
  bool empty() const
  {
  return c.empty();
  }
  void push(const T& elem)
  {
  c.push_back(elem);
  }
  T pop()
  {
  if (c.empty())
  {
    throw ReadEmptyStack();
  }
  T elem(c.back());
  c.pop_back();
  return elem;
  }
  T& top()
  {
  if (c.empty())
  {
    throw ReadEmptyStack();
  }
  return c.back();
  }
};
int main(void)
{
  try
  {
  Stack<int> st;
  st.push(1);
  st.push(2);
  st.push(3);
  st.push(4);
  cout << st.pop() << endl;
  cout << st.pop() << endl;
  st.top() = 77;  //修改栈顶元素为77
  st.push(5);
  st.push(6);
  st.pop();
  cout << "st.size():" << st.size() << endl;
  while (!st.empty())
  {
    st.pop();
  }
  st.pop();
  }
  catch (const std::exception& e)
  {
  cout << e.what() << endl;
  }
  return 0;
}

和vector接口类似，是一种特殊的容器，除了具有vector的内存特性之外，专门用于对字符串的处理操作。

#include <iostream>
#include <string>
#include <cstring>
using namespace std;
int main(void)
{
  string s1;
  string s2("helloworld");
  string s3(10, 'a');
  string s4(s2);
  cout << s2 << endl;
  /*cin >> s1;
  cout << s1 << endl;*/
  s1 += "helloworld";
  if (s1 == s2)
  {
  }
  //s1 = s1 + s2;
  s1 += s2;
  cout << s1 << endl;
//string的存取
  string s("helloworld");
  cout << s[1] << endl;
  s[1] = 'x';
  for (auto it = s.begin(); it != s.end(); it++)
  {
  cout << *it << " ";
  }
  cout << endl;
  for (auto &s : s)
  {
  cout << s << " ";
  }
  cout << endl;
//string的c_str
  /*char buf[32] = { 0 };
  strcpy_s(buf, s.c_str());
  cout << buf << endl;*/
//string 的copy
  char buf[32] = { 0 };
  s.copy(buf, 5);    //拷贝前5个字节到buf中
  cout << buf << endl;
//string的长度
  cout << s.length() << endl;
  cout << s.size() << endl;
  s.reserve(100);
  cout << s.capacity() << endl;
  s.shrink_to_fit();
  cout << s.capacity() << endl;
  if (s.empty())
  {
  cout << "字符串是空" << endl;
  }
//string的赋值
  s = "helloworld";
  const char *ss = "this is test";
  s1.assign(ss);
  cout << s1 << endl;
  s1.assign(ss, 7);
  cout << s1 << endl;
  s1.assign(5, 'a');  //把5个a赋值给s1
  cout << s1 << endl;
  s1.assign(s2);  //把s2 赋值给s1
  cout << s1 << endl;
  s1.assign(s4, 4, 3);  //把s4从第四个开始的三个字符赋值给当前字符串
  cout << s1 << endl;
//string的拼接
  s1 += "1234";
  cout << s1 << endl;
  s1 += s2;
  cout << s1 << endl;
  s1.append(ss);
  s1.append(s2);
  s1.append(ss, 2); //拼接ss的前两个字节
  s1.append(s2, 4, 2);
  cout << s1 << endl;
  s1.append(10, 'x');
  cout << s1 << endl;
//string的比较
  if (s1 == s2)
  {
  }
  if (s1.compare(s2) > 0)
  {
  }
  if (s1.compare(ss) < 0)
  {
  cout << "s1 < ss" << endl;
  }
//string字串
  cout << s1.substr() << endl;
  cout << s1.substr(5, 6)<<endl;  //从第五个开始，往后输出6个字符
//string的查找和替换
  int p = s1.find('o');
  cout << p << endl;
  p = s1.find('o', 8); //从第八个字符向后找 ,不存在返回-1
  cout << p << endl;
  p = s1.find("ll");
  cout << p << endl;
  p = s1.find(s2);
  cout << p << endl;
  p = s1.find(ss);
  cout << p << endl;
  p = s1.rfind('o');
  cout << p << endl;
  s1.replace(5, 3, "xxx");
  cout << s1 << endl;
  string s9("helloworldhelloworldhelloworldhelloworldhelloworldhelloworld");
  //使用上述任意方法，将s3中所有"world"替换成"x"
  p = s9.find("world");
  while (p != -1)
  {
  s9.replace(p, strlen("world"), "x");
  p = s9.find("world", p + strlen("x"));
  }
  cout << s9 << endl;
//string的插入和删除
  s1.insert(0, "this is");
  cout << s1 << endl;
  s1.insert(10, s2);
  cout << s1 << endl;
  s1.insert(0, 5, 'x');
  cout << s1 << endl;
  s1.erase(s1.begin());
  cout << s1 << endl;
  s1.erase(0, 20);
  cout << s1 << endl;
  s1.erase(++s1.begin(),s1.end());
  cout << s1 << endl;
  return 0;
}