C++STL commonly used search algorithm
learning target:
Master commonly used search algorithms
Introduction to the algorithm:
find //查找元素
find_if //按条件查找元素
adjacent_find //查找相邻重复元素
bitary_search //二分查找法
count //统计元素个数
count_if //按条件统计元素个数
Find function description:
Find the specified element, find an iterator to return the specified element, find the iterator to return to the end, end()
Function prototype:
find(iterator beg, iterator end, value);
按值查找元素,找到返回指定位置迭代器,找不到返回结束迭代器位置
beg开始迭代器
end结束迭代器
value查找的元素
Code example:
#include<iostream>
#include<vector>
#include<algorithm>
#include<string>
using namespace std;
//查找 内置数据类型
void test01()
{
vector<int>v;
for (int i = 0; i < 10; i++)
{
v.push_back(i);
}
//查找 容器中 是否有5这个元素
vector<int>::iterator it = find(v.begin(), v.end(), 5);
if (it == v.end())
{
cout << "没有找到!" << endl;
}
else
{
cout << "找到:" << *it << endl;
}
}
class Person
{
public:
Person(string name, int age)
{
this->m_Name = name;
this->m_Age = age;
}
//重载==底层find知道如何对比persin数据类型
bool operator==(const Person &p)
{
if (this->m_Name == p.m_Name&&this->m_Age == p.m_Age)
{
return true;
}
else
{
return false;
}
}
string m_Name;
int m_Age;
};
void test02()
{
vector<Person>v;
//创建数据
Person p1("aaa", 10);
Person p2("bbb", 20);
Person p3("ccc", 30);
Person p4("ddd", 40);
//放入到容器中
v.push_back(p1);
v.push_back(p2);
v.push_back(p3);
v.push_back(p4);
Person pp("bbb", 20);
vector<Person>::iterator it = find(v.begin(), v.end(), pp);
if (it == v.end())
{
cout << "没有找到" << endl;
}
else
{
cout << "找到元素 姓名:" << it->m_Name << " 年龄:"<<it->m_Age << endl;
}
}
int main()
{
//test01();
test02();
system("pause");
return 0;
}
Summary: Use find to find the specified element in the container, and the return value is an iterator