（c++笔记）第三十一节课：异常与容器适配器

一 multimap

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 
#include 
#include 
#include 
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："< 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;

}

二 deque

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 
#include 
#include 
using namespace std;

int main(void)
{
    int data[5] = { 1,2,3,4,5 };
    deque d1;
    deque d2(data, data + 5);
    deque 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;

}

三容器适配器

stack（LIFO）
queue(fifo)
priority_queue()

3.1 stack

#include 
#include 
#include 
using namespace std;
int main(void)
{
    stack 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;
}

3.2 队列

#include 
#include 
#include 
using namespace std;
int main(void)
{
    queue 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：" < 
3.3 优先队列 
#include 
#include 
#include 
using namespace std;
int main(void)
{
    //priority_queue p;
    //priority_queue, less> p;  //等价于priority_queue p;
    priority_queue, greater> 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"< 
四 异常 
4.1 什么是异常 
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） 
4.2 异常的语法 
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 
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;
} 
4.3 异常的声明 
#include 
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;

} 
4.4 异常对象 
#include 
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)
    {
        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;
} 
4.5 标准异常库 
 
#include 
#include 
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;
} 
4.6 自定义stack 
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 
#include 
#include 
using namespace std;
template 
class Stack
{
protected:
    std::deque c;
public:
    class ReadEmptyStack :public exception
    {
    public:
        virtual const char* what() const throw()
        {
            return "read empty stack";
        }
    };
    //typename std::deque::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 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;
} 
五 string 
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 
#include 
#include 
using namespace std;

int main(void)
{
    string s1;
    string s2("helloworld");
    string s3(10, 'a');
    string s4(s2);

    cout << s2 << 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
    
//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)<

（c++笔记）第三十一节课：异常与容器适配器

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