unordered_map.erase(const key);

unordered_map.erase(const iteratorStart, const iteratorEnd);

// CPP program to demonstrate implementation of
// erase function in unordered_map.
# include <bits/stdc++.h>
using namespace std;
  
int main()
{
  
    unordered_map<int, bool> um;
  
    // Adding some elements in the map.
    um[12] = true;
    um[4189] = false;
    um[519] = true;
    um[40] = false;
    um[4991] = true;
  
    cout << "unordered_map的内容：\n";
    for (auto p : um)
        cout << p.first << "==>" << p.second << "\n";
    cout << "\n";
  
    // 按迭代器删除
    cout << "按迭代器删除后：\n";
    um.erase(um.begin());
    for (auto p : um)
        cout << p.first << "==>" << p.second << "\n";
    cout << "\n";
  
    // 按键删除
    cout << "按键删除后：\n";
    um.erase(4189);
    for (auto p : um)
        cout << p.first << "==>" << p.second << "\n";
    cout << "\n";
  
    // 按范围删除
    cout << "按范围删除后：\n";
    auto it = um.begin();
    it++; // 返回指向第二个元素的迭代器
    um.erase(it, um.end());
    for (auto p : um)
        cout << p.first << "==>" << p.second << "\n";
    cout << "\n";
  
    return 0;
}

unordered_map的内容：
4991==>1
519==>1
40==>0
12==>1
4189==>0

按迭代器删除后：
519==>1
40==>0
12==>1
4189==>0

按键删除后：
519==>1
40==>0
12==>1

按范围删除后：
519==>1