c++中std::map移除元素

可以使用 `erase()` 成员函数来移除 `std::map` 中的元素。该函数接受一个键作为参数，并返回被移除元素的个数。如果该键不存在，则返回 0。以下是一个示例代码：

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

int main() {
    std::map<std::string, int> people {
        {"Fred", 45},
        {"Joan", 33},
        {"Jill", 22}
    };

    std::string name{"Joan"};
    int count = people.erase(name);
    if (count) {
        std::cout << name << " was removed." << std::endl;
    } else {
        std::cout << name << " was not found." << std::endl;
    }

    // 遍历 map
    for (const auto& p : people) {
        std::cout << std::setw(10) << std::left << p.first << " " << p.second << "\n";
    }

    return 0;
}

输出结果为：

Joan was removed.
Fred       45
Jill       22