2.map大小和交换

#include<iostream>
using namespace std;

#include<map>

void Printmap(map<int, int> m)
{
    for (map<int, int>::iterator it = m.begin(); it != m.end(); it++)
    {
        cout << "key:" << it->first << "\t"
            << "value:" << it->second << endl;
    }
}
void test0201()
{
    map<int, int> m1;
    m1.insert(pair<int, int>(1, 10));
    m1.insert(pair<int, int>(2, 20));
    m1.insert(pair<int, int>(3, 30));
    m1.insert(pair<int, int>(4, 40));

    if (m1.empty())
    {
        cout << "m1为空" << endl;
    }
    else
    {
        cout << "m1不为空" << endl;
        cout << "m1的大小：" << m1.size() << endl;
    }

    map<int, int> m2;
    m2.insert(pair<int, int>(5, 50));
    m2.insert(pair<int, int>(6, 60));
    m2.insert(pair<int, int>(7, 70));
    m2.insert(pair<int, int>(8, 80));

    cout << "交换前：" << endl;
    Printmap(m1);
    Printmap(m2);

    m2.swap(m1);
    cout << "交换后：" << endl;
    Printmap(m1);
    Printmap(m2);
}
int main()
{
    test0201();

    system("pause");
    return 0;
}