#include <iostream>
#include <set>
using namespace std;

int main() {
    set<int> s;
    s.insert(1);
    //返回值为pair<set<int>::iterator, bool>
    //迭代器表示该元素的位置 
    cout << *s.insert(1).first << endl;
    cout << s.insert(1).second << endl; 
    //输出1 和 0 
}


如

#include <iostream>
#include <set>
#include <string>
#include <string.h>

using namespace std;

class Student
{
public:
  Student(char*name,int age)
  {
    strcpy(this->name,name);
    this->age=age;
  }
public:
  int age;
  char name[64];
};

//仿函数
struct FuncStudent
{
  bool operator()(const Student&left,const Student &right)
  {
    if(left.age<right.age)//如果左边的值小就返回真，即从小到大安装年龄排序
    {
      return true;
    }
    else
    {
      return false;
    }
  }
};

int main()
{
  Student s1("s1",31);
  Student s2("s2",22);
  Student s3("s3",44);
  Student s4("s4",11);
  Student s5("s5",31);
  set<Student,FuncStudent> set1;
  //如何判断set1.insert()函数的返回值
  //typedef pair<iterator, bool> _Pairib;
  pair<set<Student,FuncStudent>::iterator,bool> pair1=set1.insert(s1);
  if(pair1.second==true)
  {
    cout<<"插入s1成功"<<endl;
  }
  else
  {
    cout<<"插入s1失败"<<endl;
  }
  set1.insert(s2);
  pair<set<Student,FuncStudent>::iterator,bool> pair5=set1.insert(s5);
  if(pair5.second==true)
  {
    cout<<"插入s5成功"<<endl;
  }
  else
  {
    cout<<"插入s5失败"<<endl;
  }

  //遍历
  for(set<Student,FuncStudent>::iterator it=set1.begin();it!=set1.end();it++)
  {
    cout<<it->age<<"\t"<<it->name<<endl;
  }

  system("pause");
  return 0;
}

C++ std::set insert 怎么得到 返回值 是什么_#include