C++ STL02三大组件的基本使用

STL 中的容器 算法 迭代器

1. 头文件

#define _CRT_SECURE_NO_WARNINGS
#include<iostream>//输入输出流
#include<vector>//容器
#include<algorithm>//算法
using namespace std;

基本用法

void test1(){
	vector<int> v; //STL 中的标准容器之一 ：动态数组
	v.push_back(1); //vector 容器提供的插入数据的方法
	v.push_back(5);
	v.push_back(3);
	v.push_back(7);
	//迭代器
	vector<int>::iterator pStart = v.begin(); //vector 容器提供了 begin()方法 返回指向第一个元素的迭代器
	vector<int>::iterator pEnd = v.end(); //vector 容器提供了 end()方法 返回指向最后一个元素下一个位置的迭代器
	//通过迭代器遍历
	while (pStart != pEnd){
		cout << *pStart << " ";
		pStart++;
	}
	cout << endl;
	//算法 count 算法 用于统计元素的个数
	int n = count(pStart, pEnd, 5);
	cout << "n:" << n << endl;
}
//STL 容器不单单可以存储基础数据类型，也可以存储类对象
class Teacher
{
public:
	Teacher(int age) :age(age){};
	~Teacher(){};
public:
	int age;
};

存储 Teacher 类型

void test2(){
	vector<Teacher> v; //存储 Teacher 类型数据的容器
	Teacher t1(10), t2(20), t3(30);
	v.push_back(t1);
	v.push_back(t2);
	v.push_back(t3);
	vector<Teacher>::iterator pStart = v.begin();
	vector<Teacher>::iterator pEnd = v.end();
	//通过迭代器遍历
	while (pStart != pEnd){
		cout << pStart->age << " ";
		pStart++;
	}
	cout << endl;
}

存储 Teacher 类型指针

//存储 Teacher 类型指针
void test3(){
	vector<Teacher*> v; //存储 Teacher 类型指针
	Teacher* t1 = new Teacher(10);
	Teacher* t2 = new Teacher(20);
	Teacher* t3 = new Teacher(30);
	v.push_back(t1);
	v.push_back(t2);
	v.push_back(t3);
	//拿到容器迭代器
	vector<Teacher*>::iterator pStart = v.begin();
	vector<Teacher*>::iterator pEnd = v.end();
	//通过迭代器遍历
	while (pStart != pEnd){
		cout << (*pStart)->age << " ";
		pStart++;
	}
	cout << endl;
}

容器嵌套容器 难点

//容器嵌套容器 难点
void test4()
{
	vector< vector<int> > v;
	vector<int>v1;
	vector<int>v2;
	vector<int>v3;

	for (int i = 0; i < 5;i++)
	{
		v1.push_back(i);
		v2.push_back(i * 10);
		v3.push_back(i * 100);
	}
	v.push_back(v1);
	v.push_back(v2);
	v.push_back(v3);

	for (vector< vector<int> >::iterator it = v.begin(); it != v.end();it++)
	{
		for (vector<int>::iterator subIt = (*it).begin(); subIt != (*it).end(); subIt ++)
		{
			cout << *subIt << " ";
		}
		cout << endl;
	}
} 

主函数main

int main(){
	//test1();
	//test2();
	//test3();
	test4();
	system("pause");
	return EXIT_SUCCESS;
}