4、stl-string

容器的分类
序列式容器：每个元素都有固定的位置，取决于插入删除的时机，和元素值没有关系
vector、deque、list
关联式容器：元素位置取决于特定的排序准则，和插入顺序无关
set、multiset、map、multimap

string类对char * 的封装

#include <iostream>
using namespace std;
#include "string"
#include "algorithm"

//string的初始化
void main21()
{
    string s1 = "aaaa";
    string s2("bbbb");
    string s3 = s2; //通过拷贝构造函数 来初始化对象s3
    string s4(10, 'a');

    cout << "s1:" << s1 << endl;
    cout << "s2:" << s2 << endl;
    cout << "s3:" << s3 << endl;
    cout << "s4:" << s4 << endl;
}

//string的 遍历
void main22()
{
    string s1 = "abcdefg";

    //1 数组方式
    for (int i=0; i<s1.length(); i++)
    {
        cout << s1[i] << " ";
    }
    cout << endl;

    //2 迭代器
    for (string::iterator it = s1.begin(); it != s1.end(); it++ )
    {
        cout << *it << " ";
    }
    cout << endl;

    try
    {
        for (int i=0; i<s1.length() + 3; i++)
        {
            cout << s1.at(i) << " ";  //抛出异常
        }
    }
    catch ( ... )
    {
        cout << "发生异常\n" ;
    }

    cout << "at之后" << endl;
    /*
    try
    {
        for (int i=0; i<s1.length() + 3; i++)
        {
            cout << s1[i] << " "; //出现错误 不向外面抛出异常 引起程序的中断
        }
    }
    catch ( ... )
    {
        cout << "发生异常\n" ;
    }
    */

}

//字符指针和string的转换
void main23()
{
    string s1 = "aaabbbb";

    //1 s1===>char *
    //printf("s1:%s \n", s1.c_str());

    //2 char *====>sting 


    //3 s1的内容 copy buf中
    //char buf1[128] = {0};
    //s1.copy(buf1, 3, 0);  //注意 只给你copy3个字符 不会变成C风格的字符串
    //cout << "buf1:" << buf1 << endl; 
}

//字符串的 连接
void main24()
{
    string s1 = "aaa";
    string s2 = "bbb";
    s1 = s1 + s2;
    cout << "s1:" << s1 << endl;

    string s3 = "333";
    string s4 = "444";
    s3.append(s4);
    cout << "s3:" << s3 << endl;
}


//字符串的查找和替换
void main25()
{
    string s1 = "wbm hello wbm 111  wbm 222  wbm 333 ";
    //           ▲
    //第一次 出现wbm index

    int index = s1.find("wbm", 0); //位置下标 从0开始
    cout << "index: " << index << endl;

    //案例1 求wbm出现的次数 每一次出现的数组下标
    int offindex = s1.find("wbm", 0);
    while (offindex != string::npos)
    {
        cout << "offindex:" << offindex << endl;
        offindex = offindex + 1;
        offindex = s1.find("wbm", offindex); //wang bao ming 
    }

    //案例2  把小写wbm===>WBM

    string s3 = "aaa  bbb ccc";
    s3.replace(0, 3, "AAA");
    cout << "s3" << s3 << endl;

    offindex = s1.find("wbm", 0);
    while (offindex != string::npos)
    {
        cout << "offindex:" << offindex << endl;
        s1.replace(offindex,3, "WBM");
        offindex = offindex + 1;
        offindex = s1.find("wbm", offindex); //
    }

    cout << "s1替换后的结果: " << s1 << endl;

}


//截断（区间删除）和插入
void main26()
{
    string s1 = "hello1 hello2 hello1";
    string::iterator it = find(s1.begin(), s1.end(), 'l');
    if (it != s1.end() )
    {
        s1.erase(it);
    }
    cout << "s1删除l以后的结果:" << s1 << endl;

    s1.erase(s1.begin(), s1.end() );
    cout << "s1全部删除:" << s1 << endl;
    cout << "s1长度 " << s1.length() << endl;

    string s2 = "BBB";

    s2.insert(0, "AAA"); // 头插法
    s2.insert(s2.length(), "CCC");

    cout << s2 << endl;
}

void main27()
{
    string s1 = "AAAbbb";
    //1函数的入口地址 2函数对象 3预定义的函数对象
    transform(s1.begin(), s1.end(),s1.begin(), toupper);
    cout << "s1" << s1 << endl;

    string s2 = "AAAbbb";
    transform(s2.begin(), s2.end(), s2.begin(), tolower);
    cout << "s2:" << s2 << endl;

}


void main2222()
{
    //main21();
    //main22();
    //main23();
    //main24();
    //main25();
    //main26();
    main27();
    cout<<"hello..."<<endl;
    system("pause");
    return ;
}