C++的查增删操作

你的名字 2021-09-19 06:40 253阅读 0赞

**一 代码**

#include <iostream>
    #include <string>
    #include <set>
    #include <string.h>
    #include <iterator>
    using namespace std;
    struct strLess{
       bool operator() (const char *s1, const char *s2) const {
        return strcmp(s1, s2) < 0;
       }
    };
    void printSet(set<int> s){
        copy(s.begin(), s.end(), ostream_iterator<int>(cout, ", ") );
        /*
        set<int>::iterator iter;
        for (iter = s.begin(); iter != s.end(); iter++)
            cout<<"set["<<iter-s.begin()<<"]="<<*iter<<", "; //Error
        cout<<*iter<<", ";
        */
        cout<<endl;
    }
    
    int main(){
        /*创建set对象，共5种方式，提示如果比较函数对象及内存分配器未出现，即表示采用的是系统默认方式*/
        /*创建空的set对象，元素类型为int，*/
        set<int> s1;
        /*创建空的set对象，元素类型char*，比较函数对象(即排序准则)为自定义strLess*/
        set<const char*, strLess> s2( strLess);
        /*利用set对象s1,拷贝生成set对象s2*/
        set<int> s3(s1);
        /*用迭代区间[&first, &last)所指的元素，创建一个set对象*/
        int iArray[] = {13, 32, 19};
        set<int> s4(iArray, iArray + 3);
        /*用迭代区间[&first, &last)所指的元素，及比较函数对象strLess，创建一个set对象*/
        const char* szArray[] = {"hello", "dog", "bird" };
        set<const char*, strLess> s5(szArray, szArray + 3, strLess() );
        /*元素插入：
        1,插入value，返回pair配对对象，可以根据.second判断是否插入成功。(提示:value不能与set容器内元素重复)
        pair<iterator, bool> insert(value)
        2,在pos位置之前插入value，返回新元素位置，但不一定能插入成功
        iterator insert(&pos, value)
        3,将迭代区间[&first, &last)内所有的元素，插入到set容器
        void insert[&first, &last);
        */
        cout<<"s1.insert() : "<<endl;
        for (int i = 0; i <5 ; i++)
            s1.insert(i*10);
        printSet(s1);
        
        cout<<"s1.insert(20).second = "<<endl;
        if (s1.insert(20).second)
            cout<<"Insert OK!"<<endl;
        else
            cout<<"Insert Failed!"<<endl;
        cout<<"s1.insert(50).second = "<<endl;
        if (s1.insert(50).second){
            cout<<"Insert OK!"<<endl;
            printSet(s1);
        }else
            cout<<"Insert Failed!"<<endl;
        cout<<"pair<set<int>::iterator, bool> p;\np = s1.insert(60);\nif (p.second):"<<endl;
        pair<set<int>::iterator, bool> p;
        p = s1.insert(60);
        if (p.second){
            cout<<"Insert OK!"<<endl;
            printSet(s1);
        }
        else
            cout<<"Insert Failed!"<<endl;
    
       /*元素删除
        1,size_type erase(value) 移除set容器内元素值为value的所有元素，返回移除的元素个数
        2,void erase(&pos) 移除pos位置上的元素，无返回值
        3,void erase(&first, &last) 移除迭代区间[&first, &last)内的元素，无返回值
        4,void clear()， 移除set容器内所有元素*/
        cout<<"\ns1.erase(70) = "<<endl;
        s1.erase(70);
        printSet(s1);
        cout<<"s1.erase(60) = "<<endl;
        s1.erase(60);
        printSet(s1);
    
        cout<<"set<int>::iterator iter = s1.begin();\ns1.erase(iter) = "<<endl;
        set<int>::iterator iter = s1.begin();
        s1.erase(iter);
        printSet(s1);
    
        /*元素查找
        count(value)返回set对象内元素值为value的元素个数
        iterator find(value)返回value所在位置，找不到value将返回end()
        lower_bound(value),upper_bound(value), equal_range(value)*/
        cout<<"\ns1.count(10) = "<<s1.count(10)<<", s1.count(80) = "<<s1.count(80)<<endl;
        cout<<"s1.find(10) : ";
        if (s1.find(10) != s1.end())
            cout<<"OK!"<<endl;
        else
            cout<<"not found!"<<endl;
        
        cout<<"s1.find(80) : ";
        if (s1.find(80) != s1.end())
            cout<<"OK!"<<endl;
        else
            cout<<"not found!"<<endl;
        /*其它常用函数*/
        cout<<"\ns1.empty()="<<s1.empty()<<", s1.size()="<<s1.size()<<endl;
        set<int> s9;
        s9.insert(100);
        cout<<"s1.swap(s9) :"<<endl;
        s1.swap(s9);
        cout<<"s1: "<<endl;
        printSet(s1);
        cout<<"s9: "<<endl;
        printSet(s9);
        return 0;
    }

**二 运行**

[root@localhost charpter03]# g++ 0331.cpp -o 0331
    [root@localhost charpter03]# ./0331
    s1.insert() :
    0, 10, 20, 30, 40,
    s1.insert(20).second =
    Insert Failed!
    s1.insert(50).second =
    Insert OK!
    0, 10, 20, 30, 40, 50,
    pair<set<int>::iterator, bool> p;
    p = s1.insert(60);
    if (p.second):
    Insert OK!
    0, 10, 20, 30, 40, 50, 60,
    
    s1.erase(70) =
    0, 10, 20, 30, 40, 50, 60,
    s1.erase(60) =
    0, 10, 20, 30, 40, 50,
    set<int>::iterator iter = s1.begin();
    s1.erase(iter) =
    10, 20, 30, 40, 50,
    
    s1.count(10) = 1, s1.count(80) = 0
    s1.find(10) : OK!
    s1.find(80) : not found!
    
    s1.empty()=0, s1.size()=5
    s1.swap(s9) :
    s1:
    100,
    s9:
    10, 20, 30, 40, 50,