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3. map::erase

map::erase

描述 (Description)

C ++函数std::map::erase()从位置移除地图的单个元素。

该成员函数将地图的大小减小一个。

声明 (Declaration)

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

C++11

iterator erase (const_iterator position);

参数 (Parameters)

position - 要移除的元素的迭代器。

返回值

返回最后一个删除元素后的迭代器。

异常 (Exceptions)

该成员函数不会抛出异常。

时间复杂

对数即log（n）。

例子 (Example)

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