#include<iostream>
#include<string>
using namespace std;
void test01()//构造函数
{
    string s1;
    cout<<"s1 = "<<s1<<endl;

    const char * str="hello world!";
    string s2(str);
    cout<<"s2 = "<<s2<<endl;

    string s3(s2);
    cout<<"s3 = "<<s3<<endl;

    string s4(10,'a');
    cout<<"s4 = "<<s4<<endl;
}
void test02()//string 赋值操作
{
    string s1;
    s1="hello";
    cout<<"s1 = "<<s1<<endl;

    string s2;
    s2=s1;
    cout<<"s2 = "<<s2<<endl;

    string s3;
    s3='a';
    cout<<"s3 = "<<s3<<endl;

    string s4;
    s4.assign("hello c++");
    cout<<"s4 = "<<s4<<endl;

    string s5;
    s5.assign("hello c++",5);
    cout<<"s5 = "<<s5<<endl;

    string s6;
    s6.assign(s5);
    cout<<"s6 = "<<s6<<endl;

    string s7;
    s7.assign(10,'w');
    cout<<"s7 = "<<s7<<endl;

}
void test03()//字符串拼接
{
    string s1;
    string s2;
    s1.assign("hello ");
    s2.assign("c++");
    //s1+=s2;
    //s1+="world";
    //s1+='w';
    //s1.append("world",2);
    //s1.append(s2);
    //s1.append(s2,1);
    cout<<"s1 = "<<s1<<endl;

}
void test04()//字符串查找
{
    string str1="abcdefgde";

    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
    //rfind从右往左查找 find从左往右查找
    pos=str1.rfind("de");

    cout<<"pos ="<<pos<<endl;

}
void test05()//字符串替换
{
    string str1 = "abcdefg";

    //从1号位置起3个字符替换为“1111”
    str1.replace(1,3,"1111");

    cout<<"str1 = "<<str1<<endl;
}
void test06()//字符串比较
{
    string str1 = "xello";
    string str2 = "hello";

    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;
}
void test07()//字符串存取
{
    string str1 = "hello";
    //通过[]访问
    for(int i = 0; i < str1.size(); i++)
        cout<<"str["<<i<<"] = "<<str1[i]<<endl;

    cout<<"--------------"<<endl;
    //通过at方式访问
    for(int i = 0; i < str1.size(); i++)
        cout<<"str["<<i<<"] = "<<str1.at(i)<<endl;
    cout<<"--------------"<<endl;
    //修改
    str1[0]='x';
    cout<<"str1[0] = "<<str1[0]<<endl;

    str1.at(0)='h';
    cout<<"str1[0] = "<<str1.at(0)<<endl;
}
void test08()//字符串插入和删除
{
    string s1="hello";

    //插入
    s1.insert(1,"111");
    cout<<"s1 = "<<s1<<endl;

    s1.insert(1,3,'a');
    cout<<"s1 = "<<s1<<endl;

    //删除
    s1.erase(1,3);
    cout<<"s1 = "<<s1<<endl;
    s1.erase(1,3);
    cout<<"s1 = "<<s1<<endl;
}
void test09()//子串
{
    string str = "abcdef";
    string sub=str.substr(1,3);
    cout<<"sub = "<<sub<<endl;

    //实用操作
    string email = "zhangsan@sina.com";

    //从邮件地址中 获取 用户名信息
    int len=email.find('@');
    sub = email.substr(0,len);
    cout<<"用户名 = "<<sub<<endl;
}
int main()
{
    //test01();//构造函数
    //test02();//赋值操作
    //test03();//拼接
    //test04();//查找
    //test05();//替换
    //test06();//比较
    //test07();//存取
    //test08();//插入和删除
    test09();//子串
    return 0;
}