C++STLmap search and statistics

C++STLmap search and statistics

Function description:
*
Search data and statistical data for the map container.
Function prototype:

find(key);           //查找key是否存在，若还在，返回改键的元素的迭代器，若不存在set.end（）；
count(key);          //统计key的元素个数

Code example:

#include<iostream>
#include<map>
using namespace std;
//map容器  查找合同及
void test01()
{
    
    
       //查找
       map<int, int>m;
       m.insert(pair<int, int>(1, 10));
       m.insert(pair<int, int>(2, 20));
       m.insert(pair<int, int>(3, 30));
       map<int, int>::iterator pos = m.find(3);
       if (pos != m.end())
       {
    
    
              cout << "查找到元素 key=" << (*pos).first << " value=" << pos->second << endl;
       }
       else
       {
    
    
              cout << "未找到元素" << endl;
       }
       //统计
       //map容器不允许插入重复值key元素，count统计而言  结果要么是0要么是1
       //multimap的count统计可能大于1
       int num = m.count(3);
       cout << "num=" << num << endl;
}
int main()
{
    
    
       test01();
       system("pause");
       return 0;
}

to sum up:

Find—find (returned is an iterator)

Statistics—count (for map, the result is 0 or 1)