C++中常见容器类的使用方法详解(vector/deque/map/set)

#include <iostream>
#include <vector>

using namespace std;

int main()
{
    vector<int> v;

    // 添加元素
    v.push_back(1);
    v.push_back(2);
    v.push_back(3);

    // 遍历元素
    for (auto it = v.begin(); it != v.end(); ++it)
    {
        cout << *it << " ";
    }
    cout << endl;

    // 访问元素
    cout << v[0] << endl;
    cout << v.at(1) << endl;

    // 删除元素
    v.erase(v.begin() + 1);

    // 大小和容量
    cout << v.size() << endl;
    cout << v.capacity() << endl;

    return 0;
}

#include <iostream>
#include <list>

using namespace std;

int main()
{
    list<int> l;

    // 添加元素
    l.push_back(1);
    l.push_back(2);
    l.push_back(3);
    l.push_front(0);

    // 遍历元素
    for (auto it = l.begin(); it != l.end(); ++it)
    {
        cout << *it << " ";
    }
    cout << endl;

    // 访问元素
    cout << l.front() << endl;
    cout << l.back() << endl;

    // 删除元素
    l.pop_front();

    // 大小
    cout << l.size() << endl;

    return 0;
}

#include <iostream>
#include <deque>

using namespace std;

int main()
{
    deque<int> d;

    // 添加元素
    d.push_back(1);
    d.push_front(0);
    d.push_back(2);

    // 遍历元素
    for (auto it = d.begin(); it != d.end(); ++it)
    {
        cout << *it << " ";
    }
    cout << endl;

    // 访问元素
    cout << d[0] << endl;
    cout << d.at(1) << endl;

    // 删除元素
    d.pop_front();

    // 大小
    cout << d.size() << endl;

    return 0;
}

#include <iostream>
#include <map>

using namespace std;

int main()
{
    map<string, int> m;

    // 添加元素
    m["apple"] = 1;
    m["banana"] = 2;
    m.insert(make_pair("orange", 3));

    // 遍历元素
    for (auto it = m.begin(); it != m.end(); ++it)
    {
        cout << it->first << " " << it->second << endl;
    }

    // 访问元素
    cout << m["apple"] << endl;

    // 删除元素
    m.erase("banana");

    // 大小
    cout << m.size() << endl;

    return 0;
}

#include <iostream>
#include <set>

using namespace std;

int main()
{
    set<int> s;

    // 添加元素
    s.insert(1);
    s.insert(2);
    s.insert(3);

    // 遍历元素
    for (auto it = s.begin(); it != s.end(); ++it)
    {
        cout << *it << " ";
    }
    cout << endl;

    // 访问元素
    auto it = s.find(2);
    if (it != s.end())
    {
        cout << *it << endl;
    }

    // 删除元素
    s.erase(3);

    // 大小
    cout << s.size() << endl;

    return 0;
}

#include <iostream>
#include <unordered_map>

using namespace std;

int main()
{
    unordered_map<string, int> um;

    // 添加元素
    um["apple"] = 1;
    um["banana"] = 2;
    um.insert(make_pair("orange", 3));

    // 遍历元素
    for (auto it = um.begin(); it != um.end(); ++it)
    {
        cout << it->first << " " << it->second << endl;
    }

    // 访问元素
    auto it = um.find("apple");
    if (it != um.end())
    {
        cout << it->second << endl;
    }

    // 删除元素
    um.erase("banana");

    // 大小
    cout << um.size() << endl;

    return 0;
}

#include <iostream>
#include <unordered_set>

using namespace std;

int main()
{
    unordered_set<int> us;

    // 添加元素
    us.insert(1);
    us.insert(2);
    us.insert(3);

    // 遍历元素
    for (auto it = us.begin(); it != us.end(); ++it)
    {
        cout << *it << " ";
    }
    cout << endl;

    // 访问元素
    auto it = us.find(2);
    if (it != us.end())
    {
        cout << *it << endl;
    }

    // 删除元素
    us.erase(3);

    // 大小
    cout << us.size() << endl;

    return 0;
}

#include <iostream>
#include <vector>

using namespace std;

int main()
{
    vector<int> v = {1, 2, 3};

    // 访问元素
    cout << v[0] << endl;
    cout << v.at(1) << endl;

    // 判断元素是否在容器内
    if (v.size() > 0 && v[0] == 1)
    {
        cout << "1 is in the vector." << endl;
    }

    return 0;
}

#include <iostream>
#include <deque>

using namespace std;

int main()
{
    deque<int> d = {1, 2, 3};

    // 访问元素
    cout << d[0] << endl;
    cout << d.at(1) << endl;

    // 判断元素是否在容器内
    if (d.size() > 0 && d[0] == 1)
    {
        cout << "1 is in the deque." << endl;
    }

    return 0;
}

#include <iostream>
#include <set>

using namespace std;

int main()
{
    set<int> s = {1, 2, 3};

    // 查找元素
    auto it = s.find(2);
    if (it != s.end())
    {
        cout << *it << " is in the set." << endl;
    }

    // 判断元素是否在容器内
    if (s.count(1) > 0)
    {
        cout << "1 is in the set." << endl;
    }

    return 0;
}

#include <iostream>
#include <map>

using namespace std;

int main()
{
    map<string, int> m = {{"apple", 1}, {"banana", 2}, {"orange", 3}};

    // 查找元素
    auto it = m.find("banana");
    if (it != m.end())
    {
        cout << it->second << " is in the map." << endl;
    }

    // 判断元素是否在容器内
    if (m.count("apple") > 0)
    {
        cout << "apple is in the map." << endl;
    }

    return 0;
}

#include <iostream>
#include <unordered_set>

using namespace std;

int main()
{
    unordered_set<int> us = {1, 2, 3};

    // 查找元素
    auto it = us.find(2);
    if (it != us.end())
    {
        cout << *it << " is in the unordered_set." << endl;
    }

    // 判断元素是否在容器内
    if (us.count(1) > 0)
    {
        cout << "1 is in the unordered_set." << endl;
    }

    return 0;
}

#include <iostream>
#include <unordered_map>

using namespace std;

int main()
{
    unordered_map<string, int> um = {{"apple", 1}, {"banana", 2}, {"orange", 3}};

    // 查找元素
    auto it = um.find("banana");
    if (it != um.end())
    {
        cout << it->second << " is in the unordered_map." << endl;
    }

    // 判断元素是否在容器内
    if (um.count("apple") > 0)
    {
        cout << "apple is in the unordered_map." << endl;
    }

    return 0;
}