C++ Multimap 库 - erase() 函数
描述
C++ 函数 std::multimap::erase() 删除与键 k 关联的映射值。
声明
以下是 std::multimap::erase() 函数形式 std::map 头的声明。
C++98
size_type erase (const key_type& k);
C++11
size_type erase (const key_type& k);
参数
k − 要移除的元素的键。
返回值
返回删除的元素数。
异常
如果抛出异常，对容器没有影响。
时间复杂度
Logarithmic i.e. O(log n)
示例
以下示例显示了 std::multimap::erase() 函数的用法。
#include <iostream>
#include <map>
using namespace std;
int main(void) {
/* Multimap with duplicates */
multimap<char, int> m {
{'a', 1},
{'a', 2},
{'b', 3},
{'c', 4},
{'c', 5},
};
size_t ret;
cout << "Multimap contains following elements before erase operation" << endl;
for (auto it = m.begin(); it != m.end(); ++it)
cout << it->first << " = " << it->second << endl;
cout << endl;
ret = m.erase('a');
cout << "Number of value removed are = " << ret << endl;
cout << endl;
cout << "Multimap contains following elements after erase operation" << endl;
for (auto it = m.begin(); it != m.end(); ++it)
cout << it->first << " = " << it->second << endl;
return 0;
}
让我们编译并运行上面的程序，这将产生以下结果 −
Multimap contains following elements before erase operation a = 1 a = 2 b = 3 c = 4 c = 5 Number of value removed are = 2 Multimap contains following elements after erase operation b = 3 c = 4 c = 5
