问题描述

派生类存放在基类类型vector中，怎么用派生类的函数？

我已经成功将派生类存放在基类类型的vector表中，也能定位位置，就是不知道怎么使用派生类的函数，只能用基类的函数，求解啊！

#include
#include
#include
#include
using namespace std;
class people
{
public:
people()
{
name = new char[20];
code = 0;
sex = new char[8];
number = new char[20];

};bool people::operator==(const people &rhs) const{    return (code == rhs.code);};void in_mess(){    cout << ""输入名字、编号、性别、身份证号"" << endl;    cin >> name;    cin >> code;    cin >> sex;    cin >> number;      };const int consttime = 10;void out_mess(){    cout << ""名字："" << name << endl;    cout << ""编号："" << code << endl;    cout << ""性别："" << sex << endl;    cout << ""身份证号："" << number << endl;};int seach(){    return code;};void eq_SC(int a){    code = a;}

private:
char *name;
int code;
char *sex;
char *number;

};
class student : virtual public people
{
public:
student(){};
friend istream&operator>>(istream&in student &p)
{
p.in_mess();
return in;
};
void out_messs()
{
people::out_mess();
cout << ""身份：学生"" << endl;
cout << ""总学时："" << consttime << endl;

}

};
class teacher :virtual public people
{
public:
teacher()
{
teachtime = 0;

};friend istream&operator>>(istream&in teacher &p){    p.in_mess();    cout << ""身份：老师"" << endl;    cout << ""输入教学学时"" << endl;    in >> p.teachtime;    return in;}void out_messs(){    people::out_mess();    cout << ""身份：老师"" << endl;    cout << ""总学时："" << teachtime + consttime << endl;}int get_TT(){    return teachtime + consttime;}

private:
int teachtime;
};
class graduate : virtual public student
{
public:
graduate()
{
freetime = 0;
};
friend istream&operator>>(istream&in graduate &p)
{
p.in_mess();
cout << ""身份：研究生"" << endl;
cout << ""输入自由研究时间"" << endl;
in >> p.freetime;
return in;
}
void out_messs()
{
people::out_mess();
cout << ""身份：研究生"" << endl;
cout << ""总学时:"" << freetime + consttime << endl;

}int get_FT(){    return freetime+consttime;}

private:
int freetime;
};
class TA : public graduate public teacher
{
public:
TA()
{
resarch_time = 0;
};
friend istream&operator>>(istream&in TA &p)
{
p.in_mess();
cout << ""身份：助教"" << endl;
cout << ""输入做研究和一定教学工作学时"" << endl;
in >> p.resarch_time;
return in;
};
void out_messs()
{
people::out_mess();
cout << ""身份：助教"" << endl;
cout << ""总学时："" << resarch_time +consttime+get_FT()+get_TT() << endl;
};
private:
int resarch_time;
};
void main()
{
cout << ""当前为空表，请输入第一个人员的信息"" << endl;
cout << ""插入身份为 1.学生 2.老师 3.研究生 4.助教 请输入序号"" << endl;
int num=0;
people first;
cin >> num;
if (num == 1)
{
student first;
cin >> first;
}
else if (num == 2)
{
teacher first;
cin >> first;

}
else if (num == 3)
{
graduate first;
cin >> first;

}
else if (num == 4)
{
TA first;
cin >> first;

};

vector<people>::iterator location;//迭代子vector<people>V(1 first);while (1){        int gong;        cout << ""请选择功能"" << endl;        cout << ""1.插入新的信息 2.查找 "" << endl;        cin >> gong;        if (gong == 1)        {            cout << ""插入身份为  1.学生  2.老师  3.研究生  4.助教  请输入序号"" << endl;            int num;            cin >> num;            if (num == 1)            {                student human;                cin >> human;                V.push_back(human);            }            else if (num == 2)            {                teacher human;                cin >> human;                V.push_back(human);            }            else if (num == 3)            {                graduate human;                cin >> human;                V.push_back(human);            }            else if (num == 4)            {                TA human;                cin >> human;                V.push_back(human);            };        }        else if (gong == 2)        {            people _new;            int studycodee;            cout << ""请输入他（她）的编号"" << endl;            cin >> studycodee;            _new.eq_SC(studycodee);            location = find(V.begin() V.end() _new);            if (location != V.end())            {                V[location - V.begin()].out_mess();            }            else                cout << ""未找到"" << endl;        }}

}

下面查找功能只能用到其基类的函数，用不到派生类的，我觉得是因为vector是存放的people类导致的，但是即使我将其派生并且重新放置派生类进去，它依然只认基类不认派生类函数啊！怎么办呀！

解决方案

你需要用多态，
而且vector中声明基类指针，然后来得到派生类。这样通过基类指针调用虚函数来实现对派生类的调用

 base *p = new derive()

解决方案二：
基类和派生类的虚函数表