【C++】常用容器-string容器

1.string基本概念

2.string构造函数

#include 
using namespace std;

//string容器
void test01()
{
	string s1;//创建空字符串，调用无参构造函数
	cout << "str1 = " << s1 << endl;//什么都不输出

	const char* str = "hello world";
	string s2(str); //c_string转换成了string

	cout << "str2 = " << s2 << endl;

	string s3(s2); //调用拷贝构造函数
	cout << "str3 = " << s3 << endl;

	string s4(10, 'a'); //使用n个字符c初始化
	cout << "str4 = " << s4 << endl;
}
//*************************************
int main() {

	test01();
	//test02();

	//**************************************
	system("pause");
	return 0;
}

3.string赋值操作

#include 
using namespace std;

void test01()
{
	string str1;
	str1 = "hello world";
	cout << "str1 = " << str1 << endl;

	string str2;
	str2 = str1;
	cout << "str2 = " << str2 << endl;

	string str3;
	str3 = 'a';
	cout << "str3 = " << str3 << endl;

	string str4;
	str4.assign("hello c++");
	cout << "str4 = " << str4 << endl;

	string str5;
	str5.assign("hello c++", 5);
	cout << "str5 = " << str5 << endl;

	string str6;
	str6.assign(str5);
	cout << "str6 = " << str6 << endl;

	string str7;
	str7.assign(5, 'x');
	cout << "str7 = " << str7 << endl;
}
//*************************************
int main() {

	test01();
	//test02();

	//**************************************
	system("pause");
	return 0;
}

4.string字符串拼接

#include 
using namespace std;

//string字符串拼接
//函数原型：
// string& operator+=(const char* str);            //重载+=操作符
// string& operator+=(const char c);               //重载+=操作符
// string& operator+=(const string& str);          //重载+=操作符
// string& append(const char *s);                  //把字符串S连接到当前字符串结尾
// string& append(const char *s,int n);            //把字符串S的前n个字符串连接到当前字符串结尾
// string& append(const string &s);                //同operator+=(const string& str)
// string& append(const string &s, int pos, int n);//字符串S中从pos开始的n个字符连接到字符串结尾
//********************************************************************************************

void test01()
{
	// string& operator+=(const char* str);   //重载+=操作符
	string str1 = "我";
	str1 += "爱陶子";
	cout << "str1 = " << str1 << endl;

	// string& operator+=(const char c);               //重载+=操作符
	str1 += '!';
	cout << "str1 = " << str1 << endl;

	// string& operator+=(const string& str);          //重载+=操作符
	string str2 = " Miss Tao!";
	str1 += str2;
	cout << "str1 = " << str1 << endl;

	// string& append(const char *s);                  //把字符串S连接到当前字符串结尾
	string str3 = "I";
	str3.append(" love ");
	cout << "str3 = " << str3 << endl;

	// string& append(const char *s,int n);            //把字符串S的前n个字符串连接到当前字符串结尾
	str3.append("Tao! taozi", 4);
	cout << "str3 = " << str3 << endl;

	// string& append(const string &s);                //同operator+=(const string& str)
	str3.append(str2);
	cout << "str3 = " << str3 << endl;

	// string& append(const string &s, int pos, int n);//字符串S中从pos开始的n个字符连接到字符串结尾
	str3.append(str2, 6, 4);
	cout << "str3 = " << str3 << endl;
}

int main() {

	test01();
	//test02();

	//**************************************
	system("pause");
	return 0;
}

不知道再查就好啦

5.string查找和替换

#include 
using namespace std;

//string字符串的查找和替换

//查找
void test01()
{
	string str1 = "abcdefgde";

	//find
	int pos = str1.find("de");

	if (pos == -1)
	{
		cout << "未找到" << endl;
	}
	else
	{
		cout << "pos = " << pos << endl;
	}

	//rfind
	pos = str1.rfind("de");
	cout << "pos = " << pos << endl;

	//find和rfind的区别
	//find从左往右查找   rfind从右往左查找
}

//替换
void test02()
{
	string str1 = "abcdefgde";
	str1.replace(1, 3, "1111"); //把第1到3位全部移除，将1111全部插入

	cout << "str1 = " << str1 << endl;
}

int main() {

	//test01();
	test02();

	//**************************************
	system("pause");
	return 0;
}

《查找》的结果

《替换》的结果

6.string字符串比较

#include 
using namespace std;

//string字符串比较
void test01()
{
	string str1 = "hello";
	string str2 = "delao";

	int ret = str1.compare(str2);

	if (ret == 0)
	{
		cout << "str1等于str2" << endl;
	}
	else if (ret > 0)
	{
		cout << "str1大于str2" << endl;
	}
	else
	{
		cout << "str1小于str2" << endl;
	}
}
int main() {

	test01();
	//test02();

	//**************************************
	system("pause");
	return 0;
}

7.string字符存取

#include 
using namespace std;

//string字符存取
void test01()
{
	string str = "hello";
	cout << "str = " << str << endl;

	//1、通过[]访问单个字符
	for (int i = 0; i < str.size(); i++)
	{
		cout << str[i] << " ";
	}
	cout << endl;

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

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

	str.at(1) = 'x';
	//xxlo

	cout << "str = " << str << endl;
}
int main() {

	test01();
	//test02();

	//**************************************
	system("pause");
	return 0;
}

8.string插入和删除

#include 
using namespace std;

//字符串插入和删除
void test01()
{
	string str = "hello";

	//插入
	str.insert(1, "111");
	//h111ello
	cout << str << endl;

	//删除
	str.erase(1, 3); //从1号位置开始的3个字符
	cout << str << endl;

}

int main() {

	test01();
	//test02();

	//**************************************
	system("pause");
	return 0;
}

9.string子串

#include 
using namespace std;

//string子串截取
void test01()
{
	string str = "123456";
	string subStr = str.substr(1, 3);
	cout << "subStr = " << subStr << endl;

	//实用例子-从邮箱名提取用户信息
	string email = "[email protected]";
	int pos = email.find('@');
	string usrname = email.substr(0, pos);
	cout << "Name = " << usrname << endl;
}


int main() {

	test01();
	//test02();

	//**************************************
	system("pause");
	return 0;
}