C++的查增删操作

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,

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