C++ STL 详解

char* s1 = "Hello SYSU!"; //创建指针指向字符串常量，这段字符串我们是不能修改的

//想要创建 可以修改的字符串，我们可以使用数组分配空间
char s2[20] = "Hello SYSU!";
//或者这样
char s3[] = "Hello SYSU!";

//当然我们也可以动态分配内存
char* s4 = (char*)malloc(20）;
gets(s4);

#include <string>

string s1;//初始化字符串，空字符串
string s2 = s1; //拷贝初始化，深拷贝字符串
string s3 = "I am Yasuo"; //直接初始化，s3存了字符串
string s4(10, 'a'); //s4存的字符串是aaaaaaaaaa
string s5(s4); //拷贝初始化，深拷贝字符串
string s6("I am Ali"); //直接初始化
string s7 = string(6, 'c'); //拷贝初始化，cccccc

#include <iostream>
#include <string>

using namespace std;

int main()
{
    string s1;//初始化字符串，空字符串
    string s2 = s1; //拷贝初始化，深拷贝字符串
    string s3 = "I am Yasuo"; //直接初始化，s3存了字符串
    string s4(10, 'a'); //s4存的字符串是aaaaaaaaaa
    string s5(s4); //拷贝初始化，深拷贝字符串
    string s6("I am Ali"); //直接初始化
    string s7 = string(6, 'c'); //拷贝初始化，cccccc

    //string的各种操作
    string s8 = s3 + s6;//将两个字符串合并成一个
    s3 = s6;//用一个字符串来替代另一个字符串的对用元素

    cin >> s1;

    cout << s1 << endl;
    cout << s2 << endl;
    cout << s3 << endl;
    cout << s4 << endl;
    cout << s5 << endl;
    cout << s6 << endl;
    cout << s7 << endl;
    cout << s8 << endl;
    cout << "s7 size = " << s7.size() << endl; //字符串长度，不包括结束符
    cout << (s2.empty() ? "This string is empty" : "This string is not empty") << endl;;

    system("pause");
    return 0;
}

"     Hello   World"

cin>>s1>>s2;

string str;
getline(cin, str);
cout << str << endl;

string s1 = s2 + ", "; //正确
string s3 = "s " + ", "; //错误
string s4 = "hello" + ", " + s1; //错误
string s5 = s1 + "hello " + ", "; //改一下顺序，s1放前头，正确了，注意理解=号右边的运算顺序

for (int i = 0; i < s3.size(); i++)
{
    cout << s3[i] << endl;
    s3[i] = 's';
}

string str("hi sysu");
for (string::iterator it = str.begin(); it != str.end(); it++)
{
    cout << *it << endl;
}

string str2("hi sysu");
for (string::const_iterator it = str2.begin(); it != str2.end(); it++)
{
    cout << *it << endl;
    *it = 'l'; //这是错误的，不能写
}

string sq("heoolo sdaa ss");
cout << s.find("aa", 0) << endl; //返回的是子串位置。第二个参数是查找的起始位置，如果找不到，就返回string::npos
if (s.find("aa1", 0) == string::npos)
{
    cout << "找不到该子串！" << endl;
}

#include <vector>

vector<int> v1;
vector<father> v2;
vector<string> v3;
vector<vector<int> >;  //注意空格。这里相当于二维数组int a[n][n];
vector<int> v5 = { 1,2,3,4,5 }; //列表初始化,注意使用的是花括号
vector<string> v6 = { "hi","my","name","is","lee" };
vector<int> v7(5, -1); //初始化为-1,-1,-1,-1,-1。第一个参数是数目，第二个参数是要初始化的值
vector<string> v8(3, "hi");
vector<int> v9(10); //默认初始化为0
vector<int> v10(4); //默认初始化为空字符串

for (int i = 0; i < 20; i++)
{
    v1.push_back(i);
}

for (int i = 0; i < v1.size(); i++)
{
    cout << v1[i] << endl;
    v1[i] = 100;
    cout << v1[i] << endl;
}

vector<int> vec;
vec[0] = 1;  //错误！

vector<string> v6 = { "hi","my","name","is","lee" };
for (vector<string>::iterator iter = v6.begin(); iter != v6.end(); iter++)
{
    cout << *iter << endl;
    //下面两种方法都行
    cout << (*iter).empty() << endl;
    cout << iter->empty() << endl; 
}

for (vector<string>::reverse_iterator iter = v6.rbegin(); iter != v6.rend(); iter++)
{
    cout << *iter << endl;

}

#include <iostream>
#include <vector>
#include <string>

using namespace std;

template <typename T>
void showvector(vector<T> v)
{
    for (vector<T>::iterator it = v.begin(); it != v.end(); it++)
    {
        cout << *it;
    }
    cout << endl;
}

int main()
{
    vector<string> v6 = { "hi","my","name","is","lee" };
    v6.resize(3);  //重新调整vector容量大小
    showvector(v6);

    vector<int> v5 = { 1,2,3,4,5 }; //列表初始化,注意使用的是花括号
    cout << v5.front() << endl; //访问第一个元素
    cout << v5.back() << endl; //访问最后一个元素

    showvector(v5);
    v5.pop_back(); //删除最后一个元素
    showvector(v5);
    v5.push_back(6); //加入一个元素并把它放在最后
    showvector(v5);
    v5.insert(v5.begin()+1,9); //在第二个位置插入新元素
    showvector(v5);
    v5.erase(v5.begin() + 3);  //删除第四个元素
    showvector(v5);
    v5.insert(v5.begin() + 1, 7,8); //连续插入7个8
    showvector(v5);
    v5.clear(); //清除所有内容
    showvector(v5);

    system("pause");
    return 0;
} 

#include <set>

#include <iostream>
#include <set>
#include <string>

using namespace std;

template <typename T>
void showset(set<T> v)
{
    for (set<T>::iterator it = v.begin(); it != v.end(); it++)
    {
        cout << *it;
    }
    cout << endl;
}

int main()
{
    set<int> s1{9,8,1,2,3,4,5,5,5,6,7,7 }; //自动排序，从小到大,剔除相同项
    showset(s1);
    set<string> s2{ "hello","sysy","school","hello" }; //字典序排序
    showset(s2);
    s1.insert(9); //有这个值了，do nothing
    showset(s1);
    s2.insert("aaa"); //没有这个字符串，添加并且排序
    showset(s2);
    
    system("pause");
    return 0;
} 

#include <list>

#include <iostream>
#include <list>
#include <string>

using namespace std;

template <typename T>
void showlist(list<T> v)
{
    for (list<T>::iterator it = v.begin(); it != v.end(); it++)
    {
        cout << *it;
    }
    cout << endl;
}

int main()
{
    list<int> l1{ 1,2,3,4,5,5,6,7,7 };
    showlist(l1);
    list<double> l2;
    list<char> l3(10);
    list<int> l4(5, 10); //将元素都初始化为10
    showlist(l4);

    
    system("pause");
    return 0;
} 

list<int> l1{ 8,5,7,6,1,2,3,4,5,5,6,7,7 };
l1.sort();

#include <map>

#include <iostream>
#include <map>
#include <string>

using namespace std;

void showmap(map<string, int> v)
{
    for (map<string, int>::iterator it = v.begin(); it != v.end(); it++)
    {
        cout << it->first << "  " << it->second << endl;  //注意用法，不是用*it来访问了。first表示的是key，second存的是value
    }
    cout << endl;
}

int main()
{
    map<string, int> m1; //<>里的第一个参数表示key的类型,第二个参数表示value的类型
    m1["Kobe"] = 100;
    m1["James"] = 99;
    m1["Curry"] = 98;

    string s("Jordan");
    m1[s] = 90;

    cout << m1["Kobe"] << endl;
    cout << m1["Jordan"] << endl;
    cout << m1["Durant"] << endl; //不存在这个key，就显示0

    m1.erase("Curry");//通过关键字来删除
    showmap(m1);
    m1.insert(pair<string, int>("Harris", 89)); //也可以通过insert函数来实现增加元素
    showmap(m1);
    m1.clear(); //清空全部


    system("pause");
    return 0;
}

if (m1.count("Lee"))
{
    cout << "Lee is in m1!" << endl;
}
else
{
    cout << "Lee do not exist!" << endl;
}

for (map<string, int>::iterator it = m1.begin(); it != m1.end(); it++)
{
    cout << it->first<<"  "<<it->second << endl;  //注意用法，不是用*it来访问了。first表示的是key，second存的是value
}