C++ 地图库-erase() 函数

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描述

C++ 函数std::map::erase()从位置删除映射的单个元素。

该成员函数将映射的大小减一。

宣言

以下是 std::map::erase() 函数形式 std::map 标头的声明。

C++11

iterator erase (const_iterator position);

参数

position - 要删除的元素的迭代器。

返回值

返回最后删除的元素后面的迭代器。

例外情况

该成员函数不会抛出异常。

时间复杂度

对数即log(n)。

例子

以下示例显示了 std::map::erase() 函数的用法。

#include <iostream>
#include <map>

using namespace std;

int main(void) {
   /* Initializer_list constructor */
   map<char, int> m = {
            {'a', 1},
            {'b', 2},
            {'c', 3},
            {'d', 4},
            {'e', 5},
            };

   cout << "Map contains following elements before erase operation" << endl;

   for (auto it = m.begin(); it != m.end(); ++it)
      cout << it->first << " = " << it->second << endl;

   auto it = m.erase(m.begin());

   cout << "Map contains following elements after erase operation" << endl;

   for (auto it = m.begin(); it != m.end(); ++it)
      cout << it->first << " = " << it->second << endl;

   cout << "After erase operation iterator points to = " << it->first << endl;

   return 0;
}

让我们编译并运行上面的程序，这将产生以下结果 -

Map contains following elements before erase operation
a = 1
b = 2
c = 3
d = 4
e = 5
Map contains following elements after erase operation
b = 2
c = 3
d = 4
e = 5
After erase operation iterator points to = b