stl函数的运用实例（一）

stl函数的运用实例（一）

#ifndef _ITERATOR_DEBUG_LEVEL
#define _ITERATOR_DEBUG_LEVEL 0
#else
#undef _ITERATOR_DEBUG_LEVEL
#define _ITERATOR_DEBUG_LEVEL 0
#endif

#include <iostream>
#include <string>
#include <algorithm> //算法

using namespace std;

//STL standard template libary 标准模(mu)板库 C++一部分，编译器自带
//Android NDK支持
//java.lang java.util包中API，java的一部分

//string初始化

void main()
{
    //string由c字符串衍生过来的
    string s1 = "craig david";
    string s2("7 days");
    string s3 = s2;
    string s4(10,'a');

    cout << s4 << endl;

    system("pause");
}

//string遍历
void main()
{
    string s1 = "craig david";
    //             ^
    //1 数组方式
    for (int i = 0; i < s1.length(); i++)
    {
        cout << s1[i] << endl;
    }
    //2 迭代器指针
    for (string::iterator it = s1.begin(); it != s1.end(); it++)
    {
        cout << *it << " ";
    }
    cout << endl;
    //3 at函数(charAt)
    // 可能会抛出异常
    try
    {
        for (int i = 0; i < s1.length() + 3; i++)
        {
            cout << s1.at(i) << " ";
        }
    }
    catch (...)
    {
        cout << "异常" << endl;
    }


    system("pause");
}


//string字符串->c字符串转换
void main()
{
    //string -> char*
    string s1 = "walking away";
    const char* c = s1.c_str();
    printf("%s\n",c);

    //
    string s2 = c;

    //string->char[]
    //从string中赋值字符到char[]
    char arr[50] = {0};
    s1.copy(arr,4,0);

    cout << arr << endl;

    system("pause");
}


//字符串拼接
void main()
{
    string s1 = "alan";
    string s2 = "jackson";

    //1.
    string s3 = s1 + s2;

    string s4 = " pray";

    //2.
    s3.append(s4);

    cout << s3 << endl;

    system("pause");
}

//字符串查找替换
void main()
{
    string s1 = "apple google apple iphone";
    //从0开始查找"google"的位置
    int idx = s1.find("google", 0);
    cout << idx << endl;

    //统计apple出现的次数
    int idx_app = s1.find("apple",0);
    //npos大于任何有效下标的值
    int num = 0;
    while (idx_app != string::npos)
    {
        num++;
        cout << "找到的索引:" << idx_app << endl;
        idx_app+=5;
        idx_app = s1.find("apple", idx_app);
    }

    cout << num << endl;
    system("pause");
}

void main()
{
    string s1 = "apple google apple iphone";
    //0-5（不包含5）替换为jobs
    s1.replace(0, 5, "jobs");
    cout << s1 << endl;

    //所有apple替换为jobs
    int idx = s1.find("apple", 0);
    while (idx != string::npos)
    {
        s1.replace(idx, 5, "jobs");
        idx += 5;
        idx = s1.find("apple", idx);
    }

    cout << s1 << endl;
    system("pause");
}

//删除（截取）和插入
void main()
{
    string s1 = "apple google apple iphone";
    //删除a，找到a所在的指针
    string::iterator it = find(s1.begin(),s1.end(),'g');
    //只能删除一个字符
    s1.erase(it);

    //开头末尾插入字符串
    s1.insert(0, "macos");
    s1.insert(s1.length(), " facebook");

    cout << s1 << endl;
    system("pause");
}

//java StringBuffer才可变
//String 不可变
//大小写转换
void main()
{
    string s1 = "JASON";
    //原始字符串的起始地址，原始字符串的结束地址, 目标字符串的起始地址, 函数名称
    transform(s1.begin(), s1.end()-1,s1.begin(), tolower);
    cout << s1 << endl;


    transform(s1.begin(), s1.end() - 1, s1.begin(), toupper);
    cout << s1 << endl;

    system("pause");
}


//容器
//Vector
//初始化
#include <vector>
void printVector(vector<int> &v)
{
    //通过数组的方式遍历
    for (int i = 0; i < v.size(); i++)
    {
        cout << v[i] << endl;
    }
}
void main()
{
    //1.
    vector<int> v1;
    v1.push_back(20);
    v1.push_back(40);
    v1.push_back(15);
    v1.push_back(7);

    //2.
    vector<int> v2 = v1;

    //3.部分复制
    vector<int> v3(v1.begin(),v1.begin()+2);

    printVector(v3);


    system("pause");
}

//添加 删除
void main()
{
    //添加到结尾
    vector<int> v1;
    v1.push_back(20);
    v1.push_back(40);
    v1.push_back(15);
    v1.push_back(7);

    //访问头部
    v1.front() = 11;
    //访问尾部
    v1.back() = 90;

    //删除结尾的元素
    //v1.pop_back();
    while (v1.size() > 0)
    {
        cout << "末尾的元素：" << v1.back() << endl;
        v1.pop_back();
    }

    printVector(v1);

    system("pause");
}

//数组的方式
void main()
{
    vector<int> v1;
    v1.push_back(20);
    v1.push_back(40);
    v1.push_back(15);
    v1.push_back(7);

    v1[2] = v1[2] +10;

    //容器等价于动态数组    
    vector<int> v2(10);
    for (int i = 0; i < v2.size(); i++)
    {
        v2[i] = i + 1;
    }

    printVector(v2);

    system("pause");
}

//迭代器遍历
//迭代器的种类（正向，反向迭代器）
void main()
{
    vector<int> v1;
    v1.push_back(20);
    v1.push_back(40);
    v1.push_back(15);
    v1.push_back(7);
    //正向
    for (vector<int>::iterator it = v1.begin(); it < v1.end(); it++)
    {
        cout << *it << endl;
    }
    cout << "-----------------" << endl;
    //反向迭代
    for (vector<int>::reverse_iterator it = v1.rbegin(); it < v1.rend(); it++)
    {
        cout << *it << endl;
    }

    system("pause");
}

//删除
void main()
{
    vector<int> v1(10);
    for (int i = 0; i < v1.size(); i++)
    {
        v1[i] = i + 1;
    }

    //删除指定位置
    vector<int>::iterator it = v1.begin();
    it += 3;
    v1.erase(it);

    //distance(v1.begin(), it);

    //删除区间
    v1.erase(v1.begin(), v1.begin() + 3);

    for (vector<int>::iterator it = v1.begin(); it < v1.end(); it++)
    {
        if (*it == 5)
        {        
            printf("%x\n", it);
            vector<int>::iterator tmp = v1.erase(it); //注意以后开发中编译器版本问题
            printf("%x,%x\n",it,tmp);
        }
    }

    //插入
    v1.insert(v1.begin() + 2, 100);
    v1.insert(v1.end() - 1, 200);

    printVector(v1);

    system("pause");
}

//双向队列
#include <deque>
void printDeque(deque<int>& q)
{
    for (int i = 0; i < q.size(); i++)
    {
        cout << q[i] << endl;
    }
}

void main()
{
    deque<int> d1;
    //添加到尾部
    d1.push_back(2);
    d1.push_back(10);
    //添加到头部
    d1.push_front(-90);
    d1.push_front(-30);    

    //printDeque(d1);

    //cout << d1.front() << endl;
    //cout << d1.back() << endl;

    //两个方向弹出
    //d1.pop_back();
    //d1.pop_front();

    printDeque(d1);

    //查找第一个-90元素索引位置，无需遍历
    deque<int>::iterator it = find(d1.begin(),d1.end(),-90);
    if (it != d1.end())
    {
        int idx = distance(d1.begin(), it);
        cout << "索引位置为：" << idx << endl;
    }


    system("pause");
}

//数据结构 算法 分离