string中的杂散知识点

#include<iostream>
using namespace std;
#include"string"
#include"algorithm"
int main()
{
	string s1 = "who are you ?";
	string s2(" i am your father.");
	s1 += s2;
	cout <<"s1 is : " << s1  << endl;
	cout <<"s1[2] is : "<<  s1[2]<< endl; //出现异常不会抛出异常
	cout << "s2.at(2) is : " << s1.at(2) << endl; //出现异常会抛出异常

	cout << " the size of s2 is :" << s2.size() << endl;
	cout << " the length of s2 is :" << s2.length() << endl;//两者没区别，且长度中都没有算‘\0‘

	
	//查找和替换
	int iFind = s1.find( "o",0);
	while (iFind != string::npos)
	{
		cout << "o 的位置在 ： " << iFind << endl;
		s1.replace(iFind, 1, "O");
		iFind += 1;
		iFind = s1.find("o", iFind);
	}
	cout << " 替换后的s1 ："<<s1<<endl;
	//删除
	string::iterator it = find(s1.begin(), s1.end(), ‘i‘);
	if (it != s1.end())
	{
		s1.erase(it);
	}
	cout << "删除后的s1 是： " << s1 << endl;
	//插入
	s1.insert(s1.begin(),‘A‘);
	cout << "插入A 后的s1 ：" << s1 << endl;

	transform(s1.begin(), s1.end(), s1.begin(),  toupper);
	cout << " s1 大写之后 ： " << s1 << endl;

	transform(s1.begin(), s1.end(), s1.begin(), tolower);
	cout << " s1 小写之后 ： " << s1 << endl;
	//拷贝
	char buf1[11] = { 0 };
	s1.copy(buf1, 3, 0);
	cout << " buf1 is :" << buf1 << endl;
	system("pause");
}