c++STL入门

目录

什么是STL？

vector容器

构造函数

赋值操作

vector容量和大小

vector存放内置数据类型

vector存放自定义数据类型

存放指针

vector容器嵌套容器

string容器

构造函数

赋值操作

字符串拼接

查找和替换

string字符串比较

string字符存取

string插入和删除

string子串

---

什么是STL？

stl中的东西可以重复利用，stl是为了建立数据结构与算法的一套标准

stl分为容器，算法，迭代器

stl六大组件：容器，算法，迭代器，仿函数，适配器，空间配置器

vector容器

可以理解为比较强大的数组

构造函数

#include<iostream>
#include<vector>
using namespace std;
void print(vector<int>& a) {
	for (int i = 0; i < a.size (); i++) {
		cout << a[i] << " ";
	}
	cout << endl;
}
int main() {
	//默认构造
	vector<int> a;
	for (int i = 0; i < 10; i++) {
		a.push_back(i);
	}
	print(a);
	//区间构造
	vector<int> b(a.begin(), a.end());
	print(b);
	//n个elem方式构造
	vector<int> c(10, 100);
	print(c);
	//拷贝构造
	vector<int> d(a);
	print(d);
	return 0;
}

赋值操作

#include<iostream>
#include<vector>
using namespace std;
void print(vector<int>& a) {
	for (int i = 0; i < a.size(); i++) {
		cout << a[i] << " ";
	}cout << endl;
}
int main() {

	vector<int> a;
	for (int i = 0; i < 10; i++) {
		a.push_back(i);
	}
	print(a);

	vector<int> b;
	b = a;
	print(b);

	//assign
	vector<int> c;
	c.assign(a.begin(), a.end());
	print(c);

	//n个elem
	vector<int> d;
	d.assign(10, 100);
	print(d);

	return 0;
}

vector容量和大小

#include<vector>
#include<iostream>
using namespace std;
void p(vector<int>& a) {
	for (int i = 0; i < a.size(); i++) {
		cout << a[i] << " ";
	}cout << endl;
}
int main() {
	vector<int> a;
	for (int i = 0; i < 10; i++) {
		a.push_back(i);
	}
	p(a);

	if (a.empty()) {
		cout << "空" << endl;
	}
	else {
		cout << "不空" << endl;
		cout << "容量为：" << a.capacity() << endl;
		cout << "大小为：" << a.size() << endl;
	}

	//重新指定大小
	a.resize(15,100);
	p(a);//长度过大默认用0填充，如果指定数字则用指定数字填充

	a.resize(5);
	p(a);//超出部分删除

	return 0;
}

vector存放内置数据类型

#include<iostream>
#include<algorithm>//算法头文件
#include<vector>//该容器的头文件
using namespace std;
//第三种遍历方式的函数
void print(int t) {
	cout << t << endl;
}
int main() {
	//创建容器
	vector<int> a;
	//插入数据
	a.push_back(10);
	a.push_back(20);
	a.push_back(30);
	//通过迭代器访问数据
	//起始迭代器，指向第一个元素
	vector<int>::iterator itBegin = a.begin();
	//结束迭代器，最后一个元素的下一个位置
	vector<int>::iterator itEnd = a.end();
	//遍历
	//第一种方式(复杂)
	while (itBegin != itEnd) {
		cout << *itBegin << endl;
		itBegin++;
	}
	//第二种方式
	for (vector<int> ::iterator it = a.begin(); it != a.end(); it++) {
		cout << *it << endl;
	}
	//第三种方式(STL遍历算法)
	for_each(a.begin(), a.end(),print);

	return 0;
}

vector存放自定义数据类型

#include<iostream>
#include<algorithm>
#include<vector>
#include<cstring>
using namespace std;
class person {
public:
	person(string name, int age) {
		this->m_Name = name;
		this->m_Age = age;
	}
	string m_Name;
	int m_Age;
};
int main() {

	vector<person> a;

	person p1("aaa", 10);
	person p2("bbb", 20);
	person p3("ccc", 30);

	//放入数据
	a.push_back(p1);
	a.push_back(p2);
	a.push_back(p3);

	//遍历
	for (vector<person> ::iterator it = a.begin(); it != a.end(); it++) {
		cout << "姓名：" << (*it).m_Name << " " << (*it).m_Age << endl;
	}

	return 0;
}

存放指针

#include<iostream>
#include<algorithm>
#include<vector>
#include<cstring>
using namespace std;
class person {
public:
	person(string name, int age) {
		this->m_Name = name;
		this->m_Age = age;
	}
	string m_Name;
	int m_Age;
};
int main() {

	vector<person*> a;

	person p1("aaa", 10);
	person p2("bbb", 20);
	person p3("ccc", 30);

	//放入数据
	a.push_back(&p1);
	a.push_back(&p2);
	a.push_back(&p3);

	//遍历
	for (vector<person *> ::iterator it = a.begin(); it != a.end(); it++) {
		cout << "姓名：" << (*it)->m_Name << " " << (*it)->m_Age << endl;
	}

	return 0;
}

vector容器嵌套容器

类似二维数组

#include<iostream>
#include<algorithm>
#include<vector>
using namespace std;
int main() {
	vector<vector<int>> a;
	//创建小容器
	vector<int> a1;
	vector<int> a2;
	vector<int> a3;
	//向小容器中添加数据
	for (int i = 0; i < 3; i++) {
		a1.push_back(i + 1);
		a2.push_back(i + 2);
		a3.push_back(i + 3);
	}
	//小容器放入大容器
	a.push_back(a1);
	a.push_back(a2);
	a.push_back(a3);
	//通过大容器把所有数据遍历一遍
	for (vector<vector<int>> ::iterator it = a.begin(); it != a.end(); it++) {
		for (vector<int> ::iterator vit = (*it).begin(); vit != (*it).end(); vit++) {
			cout << (*vit) << " ";
		}
		cout << endl;
	}

	return 0;
}

string容器

string可以看成c++的字符串,string本质上是一个类

构造函数

#include<iostream>
#include<string>
using namespace std;
int main() {
	//默认构造
	string s1;

	//使用字符串s初始化
	const char* str = "hello world";
	string s2(str);
	cout << "s2=" << s2 << endl;

	//拷贝构造
	string s3(s2);
	cout << "s3=" << s3 << endl;

	//用n个字符初始化
	string s4(10, 'a');
	cout << "s4=" << s4 << endl;

	return 0;
}

赋值操作

#include<iostream>
#include<string>
using namespace std;
int main() {
	//char*类型字符串，赋值给当前的字符串
	string s1 = "hello";
	cout << "s1=" << s1 << endl;
	//把字符串s赋值给当前的字符串
	string s2 = s1;
	cout << "s2=" << s2 << endl;
	//字符赋值给当前的字符串
	string s3 = "a";
	cout << "s3=" << s3 << endl;
	//把字符串s赋值给当前的字符串
	string s4;
	s4.assign("c++");
	cout << "s4=" << s4 << endl;
	//把字符串s的前n个字符赋给当前字符串
	string s5;
	s5.assign("c++", 2);
	cout << "s5=" << s5 << endl;
	//把字符串s赋值给当前的字符串
	string s6;
	s6.assign(s5);
	cout << "s6=" << s6 << endl;
	//用n个字符c赋给当前字符串
	string s7;
	s7.assign(10, 'W');
	cout << "s7=" << s7 << endl;
	return 0;
}

字符串拼接

#include<iostream>
#include<string>
using namespace std;
int main() {
	string s1 = "我";
	s1 += "爱玩游戏";
	cout << "s1=" << s1 << endl;
	s1 += ':';
	cout << "s1=" << s1 << endl;
	string s2 = "LOL";
	s1 += s2;
	cout << "s1=" << s1 << endl;

	string s3 = "I ";
	s3.append("love ");
	cout << "s3=" << s3 << endl;
	s3.append("game abcde", 4);//前4个
	cout << "s3=" << s3 << endl;
	s3.append(s2);
	cout << "s3=" << s3 << endl;
	s3.append(s2, 0, 2);//截取s2中的字符，第0个开始，截取2个
	cout << "s3=" << s3 << endl;

	return 0;
}

查找和替换

#include<iostream>
#include<string>
using namespace std;
int main() {
	//查找
	string s1 = "abcdefgde";
	int pos = s1.find("de");
	cout << pos << endl;//d的位置

	pos = s1.rfind("de");
	cout << pos << endl;
	//find从左往右查，rfind从右往左查

	//替换
	string s2 = "abcdefg";
	s2.replace(1, 3, "11111111");//1~3位置全部替换为11111111
	cout << s2 << endl;

	return 0;
}

string字符串比较

#include<iostream>
#include<string>
using namespace std;
int main() {
	//比较方式：ASC||码
	//=返回0
	//>返回1
	//<返回-1
	string s1 = "xello";
	string s2 = "hello";

	if (s1.compare(s2) == 0) {
		cout << "s1=s2" << endl;
	}
	else if (s1.compare(s2) > 0) {
		cout << "s1>s2" << endl;
	}
	else {
		cout << "s1<s2" << endl;
	}
	return 0;
}

string字符存取

#include<iostream>
#include<string>
using namespace std;
int main() {
	string s1 = "hello";
	cout << s1 << endl;

	//通过[]访问单独字符
	for (int i = 0; i < s1.size(); i++) {
		cout << s1[i] << " ";
	}
	cout << endl;
	//通过at方式访问单个字符
	for (int i = 0; i < s1.size(); i++) {
		cout << s1.at(i) << " ";
	}
	cout << endl;

	//修改单个字符
	s1[0] = 'x';
	cout << s1 << endl;

	return 0;
}

string插入和删除

#include<iostream>
#include<string>
using namespace std;
int main() {
	string s = "hello";
	//插入
	s.insert(1, "111");
	cout << s << endl;
	//删除
	s.erase(1, 3);
	cout << s << endl;
	return 0;
}

string子串

#include<iostream>
#include<string>
using namespace std;
int main() {
	string s = "abcdef";
	string sub = s.substr(1, 3);
	cout << sub << endl;

	//实用操作
	string email = "[email protected]";
	int pos=email.find("@");
	string userName = email.substr(0, pos);
	cout << userName << endl;
	
	return 0;
}

未完待续。。。。。。。。。。。。。。。