C++string容器基本概念详解

#include <iostream>
using namespace std;
#include<string>
//string 的构造函数
void test01()
{
	//默认构造
	string s1;
	 //string(const char* s);使用字符串s初始化
	const char* str = "hello,world";
	string s2(str);
	cout << "s2= " << s2 << endl;
	//string(const string& str)使用一个string对象初始化另一个string对象
	string s3(s2);
	cout << "s3= " << s3 << endl;
	//string(int n,char c);使用n个字符c初始化
	string s4(10, 'a');
	cout << s4 << endl;
}
int main()
{
	test01();
}

#include <iostream>
using namespace std;
#include<string>
//string的赋值操作
void test01()
{
	//string& operator=(const char* s)//char*类型字符串 赋值给当前的字符串
	string str1;
	str1 = "hello,world";
	cout << "str1=" <<str1<< endl;
	//string& operator=（const string &s);//把字符串s赋给当前的字符串
	string str2;
	str2 = str1;
	cout << "str2= " << str2 << endl;
	//string& operator=(char c);//字符赋值给当前的字符串
	string str3;
	str3 = 'a';
	cout << "str3= " << str3 << endl;
	//string& assign(const char *s);//把字符串赋给当前的字符串
	string str4;
	str4.assign("hello C++");
	cout << "str4= " << str4 << endl;
	//string& assign(const char *s,int n);//把字符串s的前n个字符赋给当前的字符串
	string str5;
	str5.assign("hello C++", 5);
	cout << "str5= " << str5 << endl;
	//string& assign(const string &s);//把字符串s赋给当前字符串
	string str6;
	str6.assign(str5);
	cout << "str6= " << str6 << endl;

	string str7;
	str7.assign(10, 'w');
	cout << "str7= " << str7 << endl;

}
int main()
{
	test01();
}

#include <iostream>
using namespace std;
#include<string>
//string字符串拼接
void test01()
{
	//第一种方法：重载+=操作符
	string str1 = "我";
	str1 += "爱玩游戏";
	cout << "str1= " << str1 << endl;
	str1 += ':';
	cout << "str1= " << str1 << endl;
	string str2 = "LOL";
	str1 += str2;
	cout << "str1= " << str1 << endl;
	//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;
	//把字符串s的前n个字符连接到当前字符字符串结尾
	str3.append("game abcde", 4);
	cout << "str3= " << str3 << endl;
	//用append追加一个字符串
	str3.append(str2);
	cout << "str3= " << str3 << endl;
	//字符串s从pos开始的n个字符连接到字符串结尾
	str3.append(str2, 0, 3);//参数2：从哪个位置开始截取，参数3 截取字符个数
	cout << "str3= " << str3 << endl;
}
int main()
{
	test01();
}

#include <iostream>
using namespace std;
#include<string>
//字符串的查找和替换
//1.查找
void test01()
{
	string str1 = "abcdefg";
	int pos=str1.find("de");
	if (pos == -1)
	{
		cout << "未找到字符串" << endl;
	}
	else
	{
		cout << "找到字符串pos: " << pos << endl;
	}

	//rfind
	pos=str1.rfind("de");
	cout << "pos= " << pos << endl;
	//rfind和find的区别
	//rfind从右往左查找，find从左往右查找
}
//2.替换
void test02()
{
	string str1 = "abcdefg";
	//replace在替换时，要指定从哪个位置起，多少个字符，替换成什么样的字符串
	//从1号位置起3个字符替换为"1111"
	str1.replace(1, 3, "1111");
	cout << "str1= " << str1 << endl;
}
int main()
{
	test01();
	test02();
}

#include <iostream>
using namespace std;
#include<string>
//字符串比较
void test01()
{
	string str1 = "A";
	string str2 = "a";
	if (str1.compare(str2) == 0)
	{
		cout << "str1等于str2" << endl;
	}
	else if (str1.compare(str2) > 0)
	{
		cout << "str1大于str2" << endl;
	}
	else if (str1.compare(str2) < 0)
	{
		cout << "str1小于str2" << endl;
	}

}
int main()
{
	test01();
}

#include <iostream>
using namespace std;
#include<string>
//string 字符存取
void test01()
{
	string str = "hello";
	cout << "str= " <<str << endl;
	//通过[]访问单个字符
	for (int i = 0; i < str.size(); i++)
	{
		cout << str[i] << endl;
	}
	//通过at方式访问单个字符
	for (int i = 0; i < str.size(); i++)
	{
		cout << str.at(i) << endl;
	}
	//修改单个字符
	str[0] = 'x';
	str.at(1) = 'x';
	cout << "str= " << str << endl;
}
int main()
{
	test01();
}

#include <iostream>
using namespace std;
#include<string>
//字符串的插入和删除
void test01()
{
	string str = "hello";
	//插入
	str.insert(1, "111");
	cout << "str= " << str << endl;
	//删除
	str.erase(1, 3);
	cout << "str= " << str << endl;
}
int main()
{
	test01();
}

#include <iostream>
using namespace std;
#include<string>
//string求子串
void test01()
{
	string str = "abcdef";
	string subStr = str.substr(1, 3);
	cout << "subStr= " << subStr << endl;
}
int main()
{
	test01();
}