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内容

1.对map容器的大小进行操作。

2.map容器的交换操作。

运行代码

#include <iostream>
#include <map>using namespace std;void printMap(map<int, int> &m)
{for (map<int, int>::iterator it = m.begin(); it != m.end(); it++){cout << "key:" << (*it).first << " " << "value:" << (*it).second << endl;}
}void test01()
{map<int, int> m1;m1.insert(pair<int, int>(2, 20));m1.insert(pair<int, int>(3, 30));m1.insert(pair<int, int>(4, 40));m1.insert(pair<int, int>(1, 10));if (m1.empty()) // here{cout << "容器为空" << endl;}else{cout << "容器不为空" << endl;cout << "容器大小：" << m1.size() << endl; // here}map<int, int> m2;m2.insert(pair<int, int>(5, 50));m2.insert(pair<int, int>(7, 70));m2.insert(pair<int, int>(8, 80));m2.insert(pair<int, int>(6, 60));cout << "交换前：" << endl;cout << "m1:" << endl;printMap(m1);cout << "m2:" << endl;printMap(m2);m1.swap(m2); // herecout << "交换后：" << endl;cout << "m1:" << endl;printMap(m1);cout << "m2:" << endl;printMap(m2);
}int main()
{test01();return 0;
}

输出结果