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#include <stdio.h>
#include <set>
#include <unordered_set>
#include <iostream>
#include <string>
using namespace std;
template<class T>
void printSet(const string s,const T& mset){
cout<<s<<'\t';
for(auto a:mset){
cout<<a<<'\t';
}
cout<<endl;
}
int main(){
// 声明
set<int> a;
set<int> a1 = {1,2,3};
set<int> a2(a1);
set<int> a3(a1.begin(),a1.begin());
printSet("a:", a);
printSet("a1:",a1 );
printSet("a2:", a2);
printSet("a3:", a3);
//capacity相关
cout<<"a.size(): "<<a.size()<<endl;
a.insert(1);
cout<<"after insert 1, a.size()"<<a.size()<<endl;
//set不会保存重复元素，再次插入不会报错，返回值的second为false。
auto inserted = a.insert(1);
cout<<"insert duplicate 1: "<<inserted.second<<endl;
cout<<"a.empty(): "<<a.empty()<<endl;
cout<<"a.max_size(): "<<a.max_size()<<endl;
//modifiers
a.insert(3);
printSet("after insert 3: ", a);
auto find3 = a.find(3);
a.erase(find3);
printSet("after erase3: ", a);
a.clear();
printSet("after clear:", a);
a = {1,2,3,4,5};
// Look up相关
//find 会返回一个itertor
auto f = a.find(2);
if(f!=a.end()){
cout<<"find \t"<<*f<<endl;
}else{
cout<<"not found 2"<<endl;
}
cout<<"a.find(2)\t"<<*a.find(2)<<endl;
// count
cout<<"a.count(3): "<<a.count(3)<<endl;
// equal_range
auto equal2 = a.equal_range(2);
for(auto i = equal2.first; i != equal2.second; i++){
cout<<"equal2: "<<*i<<endl;
}
/*
如果equal_range判断的值在set中不存在，返回的两个iterator相等，表示空范围。
它们不一定等于end()，比如{1,3}查找2时，两个iterator都指向3。
可以通过first == second判断没有匹配元素，也可以用find或者count判断。
注意end()不能解引用，遍历时使用[first, second)即可。
*/
auto equal6 = a.equal_range(6);
cout<<"equal6 is empty: "<<(equal6.first == equal6.second)<<endl;
cout<<"equal6.first == a.end(): "<<(equal6.first == a.end())<<endl;
cout<<"equal6.second == a.end(): "<<(equal6.second == a.end())<<endl;
// 确认set中不会有重复元素，那么如果找到，则两个iterator之差肯定为1，
// 如果找不到，那么差为0,后来发现set的iterator也不可做差运算，此处存疑。
// upper_bound 和 lower_bound
auto ub = a.upper_bound(4);
auto lb = a.lower_bound(2);
cout<<"lower_bound(2): "<<*lb<<endl;
cout<<"upper_bound(4): "<<*ub<<endl;
// 遍历操作
set<int>::iterator iter = a.begin(); // 等价于auto iter = a.begin();
for(;iter!=a.end();iter++){
cout<<*iter<<'\t';
}
return 0;
}
/* 运行结果
a:
a1: 1 2 3
a2: 1 2 3
a3:
a.size(): 0
after insert 1, a.size()1
insert duplicate 1: 0
a.empty(): 0
a.max_size(): 576460752303423487
after insert 3: 1 3
after erase3: 1
after clear:
find 2
a.find(2) 2
a.count(3): 1
equal2: 2
equal6 is empty: 1
equal6.first == a.end(): 1
equal6.second == a.end(): 1
lower_bound(2): 2
upper_bound(4): 5
1 2 3 4 5 Program ended with exit code: 0
*/
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