#include<iostream>
#include<string>
# define N 3
using namespace std;

class Employee
{public:
   Employee();
    Employee(int n,char s,string nam,string da,string p)
    {
    num=n;
    sex=s;
    name=nam;
    date=da;
    position=p;
    }
   
   
    void set_1();
    void display();
private:
    int num;
    char sex;
    string name;
    string date;
    string position;
};

void Employee::set_1()
{
    cin>>num>>sex>>name>>date>>position;
}
 void Employee::display()
{
    cout<<num<<sex<<name<<date<<position<<endl;
}
int main(void)
{
    class Employee emp[N];
    cout<<"please enter the information"<<endl;
    for(int i=0;i<N;i++)
    emp[i].set_1();
    for(int k=0;k<N;k++)
    emp[i].display();
    return 0;
}
error LNK2001: unresolved external symbol "public: __thiscall Employee::Employee(void)" (??0Employee@@QAE@XZ)
Debug/1.exe : fatal error LNK1120: 1 unresolved externals
Error executing link.exe.

1.exe - 2 error(s), 0 warning(s)

#include<iostream>
#include<string>
# define N 3
using namespace std;

class Employee
{
public:
    Employee() {};                      //加 {}
    Employee(int n,char s,string nam,string da,string p)
    {
    num=n;
    sex=s;
    name=nam;
    date=da;
    position=p;
    }
    void set_1();
    void display();
private:
    int num;
    char sex;
    string name;
    string date;
    string position;
};

void Employee::set_1()
{
    cin>>num>>sex>>name>>date>>position;
}
void Employee::display()
{
    cout<<num<<sex<<name<<date<<position<<endl;
}
int main(void)
{
    Employee emp[N];
    cout<<"please enter the information"<<endl;
    for(int i=0;i<N;i++)
    emp[i].set_1();
    for(int k=0;k<N;k++)
    emp[k].display();
    return 0;
}

你的默认构造没加{}

已经解决!谢了