C++ std::set insert 怎么得到 返回值 是什么

Posted 2021-10-29 软件工程小施同学

#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 
}

STL中set的insert操作的返回值_可可西里-CSDN博客

 

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;
}

 set容器（如何判断set.insert()函数的返回值）_liyuqian199695的博客-CSDN博客