记录C++学习获得的经验点 2018/7/1-2018/7/7

梦里梦外; 2022-05-21 05:57 73阅读 0赞

## 由char \*list向stringvector复制字符串元素 ##

#include"stdafx.h"
    #include<iostream>
    #include<list>
    #include<vector>
    #include<array>
    #include<string>
    using namespace std;
    int main(int argc, char **argv) {
       //argc是命令行参数的个数，argv是字符二级指针，可指向一个字符串参数
        list <char *> l1;//定义一个双向循环链表l1
        array<char *, 3> strsarr;//使用stl array类型元素为char*
        strsarr[0] = const_cast<char *>("one line");
        strsarr[1] = const_cast<char *>("two lines");
        strsarr[2] = const_cast<char *>("three lines");
        for (size_t index = 0; index <= 2; index++){l1.push_back(strsarr[index]);}//给链表赋值
        vector<string> strvec;//准备好string的vector
        strvec.assign(l1.begin(),l1.end());//通过assign方法将char *元素变为string
        for (auto i : l1){
       cout << i << endl;}//输出比较
        cout << endl;
        for (auto i : strvec){
       cout << i << endl;}
        return 0;
    }

## 比较list和vector元素是否相等 ##

#include"stdafx.h"
    #include<iostream>
    #include<list>
    #include<vector>
    using namespace std;
    int main(int argc, char **argv) {
       //argc是命令行参数的个数，argv是字符二级指针，可指向一个字符串参数
        list<int> list_a;
        for (int i = 1; i <= 5; i++)list_a.push_back(i);
        vector<int> intveca{ 1,2,3 };
        vector<int> intvecb(list_a.begin(), list_a.end());
        bool same = true;
        if (intveca.size() == intvecb.size())
        {
            for (vector<int>::size_type index = 0; index != intveca.size(); index++)
            {
                if (intveca[index] != intvecb[index])
                {
                    same = false;
                    break;
                }
            }
    
        }
        else same = false;
        if (same)cout << "it's the same." << endl;
        else cout << "it's different." << endl;
         return 0;
    }

## erase函数的正确使用 ##

#include"stdafx.h"
    #include<iostream>
    #include<list>
    #include<vector>
    using namespace std;
    int main(int argc, char **argv) {
       //argc是命令行参数的个数，argv是字符二级指针，可指向一个字符串参数
        int ia[] = { 0,1,1,2,3,5,8,13,21,55,89 };
        vector<int> ivec(begin(ia), end(ia));
        list<int> lst(begin(ia), end(ia));
        cout << "origin list" << endl;
        for (auto i : lst)cout << i << " ";
        cout << endl<<"origin vector"<<endl;
        for (auto i : ivec)cout << i << " ";
        cout << endl;
        for (list<int>::iterator it1 = lst.begin(); it1 != lst.end();)if (*it1 % 2)it1 = lst.erase(it1); else it1++;
        for (vector<int>::iterator it2 = ivec.begin(); it2 != ivec.end();)if (*it2 % 2 == 0)it2 = ivec.erase(it2); else it2++;
        cout << "only even number list" << endl;
        for (auto i : lst)cout << i << " ";
        cout << endl<<"only odd number vector" << endl;
        for (auto i : ivec)cout << i << " ";
        cout << endl;
        return 0;
    }

## forward\_list 中删除元素 ##

#include"stdafx.h"
    #include<iostream>
    #include<forward_list>
    #include<vector>
    using namespace std;
    int main(int argc, char **argv) {
       //argc是命令行参数的个数，argv是字符二级指针，可指向一个字符串参数
        forward_list<int> fl1;
        for (int n = 1; n <= 18; n++)fl1.emplace_front(n);//forward_list只能不断向前添加元素
        for (auto i : fl1)cout << i << " ";
        cout << endl;
        for (forward_list<int>::iterator itr_pre = fl1.before_begin(), itr_cur = fl1.begin(); itr_cur != fl1.end();)
        {
       //before_begin()指向首前元素
            if (*itr_cur % 2)itr_cur = fl1.erase_after(itr_pre);//两个相邻的迭代器，erase_after参数是前面的那个
            else
            {
                itr_pre++;
                itr_cur++;
            }
        }
        for (auto i : fl1)cout << i <<" ";
        return 0;
    }

## 在forward\_list中查找元素并在其后插入特定符号的函数 ##

#include"stdafx.h"
    #include<iostream>
    #include<forward_list>
    #include<array>
    #include<string>
    using namespace std;
    bool func(forward_list<string> &base,const string tofind,const string toinsertafter)
    {
        bool canfind;
        forward_list<string>::iterator itr;
        for (itr = base.begin(); itr != base.end();)
        {
            if (*itr == tofind)
            {
                base.insert_after(itr, toinsertafter);
                return true;
            }
            else itr++;
        }
        if (itr == base.end()) {
            forward_list<string>::iterator itr_pre = base.before_begin();
            itr = base.begin();
            while (itr != base.end())
            {
                itr++;
                itr_pre++;
            }
            base.insert_after(itr_pre,"!!!");
            return false;
        }
    }
    int main(int argc, char **argv) {
       //argc是命令行参数的个数，argv是字符二级指针，可指向一个字符串参数
        array<string,10> strarr{
       "one","two","three","four","five","six","seven","eight","nine","ten"};
        forward_list<string> example(strarr.begin(), strarr.end());
        string aim;
        cout << "输入要查找的字符串: ";
        cin >> aim;
        if (func(example,aim, "<---"))cout << "查找成功" << endl;
        else cout << "未在表中找到" << endl;
        for (auto i : example)cout << i << " ";
        cout << endl;
        return 0;
    }