c++ string容器

看代码吧！

#include<iostream>
using namespace std;


int main() {
	//string是一个类


//string容器赋值操作 =
	cout << "string容器赋值操作" << endl ;
	string str1;
	str1 = "hellow CSDN";
	cout << str1<<endl;
	//将字符串前几个字符赋给另一个字符串
	string str2;
	str2.assign("hellow CSDN", 7);
	cout << str2 << endl;//hellow
	str2.assign(str1, 7);
	cout << str2 << endl << endl;;//CSDN

//string容器的拼接操作 append
	cout << "string容器的拼接操作" << endl ;
	string str3 = "Go!";
	str3 += str1;
	cout << str3 << endl;//Go!hellow CSDN

	string str4 = "Go!";
	str4.append(str1, 7, 4);
	cout << str4 << endl << endl;//Go!CSDN

//字符串的查找和替换find replace
	cout << "字符串的查找和替换" << endl;
	string str5 = "I love CS CSGO and CSDN";
	int pos = str5.find("CS");//find从左边开始找第一次出现的 返回所在的编号
	cout << pos << endl;//7
	pos = str5.rfind("CS");//rfind查找最后一次出现的 返回所在的编号
	cout << pos << endl;//14

	string str6;
	str6 = str5.replace(10, 4, "洛克王国");
	cout << str6 << endl<<endl; //I love CS 洛克王国and CSDN

//字符串比较 compare
	cout << "字符串比较" << endl;//相同返回0，左边大返回1，右边大返回-1
	string stra = "random";
	string strb = "random";
	string strc = "peace";
	if (stra.compare(strb)) {
		cout << "stra大" << endl;
	}
	else if(stra.compare(strb) == 0) {
		
		cout << "相等" << endl;
	}
	else {
	cout << "strb大" << endl;
	}
	cout << endl << endl;

//字符串存取  []
	cout << "字符串比较" << endl;
	for (int i=0; i <str6.size(); i++) {
		cout << str6[i];
	}
	str6[8] = 'f';
	cout << endl<< str6 << endl << endl;//I love Cf 洛克王国 and CSDN

//字符串插入与删除  insert erase
	cout << "字符串插入与删除" << endl;
	str6.erase(10, 8);//一个汉字相当两个字符
	cout << str6 << endl;//I love Cf and CSDN
	str6.insert(10, "LOL");
	cout << str6 << endl << endl;;//I love Cf LOL and CSDN

//字符串获取  substr(int pos,int len)//从那个位置开始几个
	cout << "字符串获取" << endl;
	string str7 = str6.substr(10, 3);
	cout << str7 << endl << endl;

//小测试  "[email protected]"取出QQ邮箱的QQ号
	string str = "[email protected]";
	int pos1 = str.find("@");
	string QQ = str.substr(0, pos1);
	cout << QQ << endl;

	}