为什么我在 c++ 中得到表达式必须有指向 class 类型的指针？

Question

Hey I am trying compare values of vector that store class objects to another vector of same class. I have class in seperate.h file containing following

class Student{
std::string ID;
std::string Name;
std::vector<std::string> FriendsIDs
Student(std::string ID, std::string Name, std::vector<std::string> FriendsIDs)
~Student(){}
};

and the class goes so on... the values I stored in objects are like

std::vector<Student* > List_Students = { {"123", "Sam", {"234", "435"}}, {"234", "Shane", {"435"}}, {"435", "Mitch", {"123"}}};

and so on and on the list goes (I read it from file, those are just few for testing), I want to compare the FriendsIDs with ID and if it matches it should print friends name with thier IDs. Expected output:

123, sam, 234(shane), 435(mitch)
234, shane, 435(mitch)

etc I used the bottom code that i inherit from stackoverflow, which was working until i put class into seperate.h file. I get error at last line of code (iter->Name), the error read "expression must have pointer to class type". My guess is that iter doesn't know what Name is, if so how do I point or fix this issue please. thank you

  for (Student* s : List_Students)
            {
                for (string& f : s->FriendsID)
                {
                    auto iter = find_if(List_Students.begin(), List_Students.end(), [&](Student* sf) { return sf->ID == f; });
                    if (iter != List_Students.end())
                    {
                        cout << " ( " << iter->Name << " ) " << "\n";
                    }
                }
            }

Answer 1

List_Students is a vector of Student* , so iter "points at" Student* . Therefore you have to do "dereferencing" two times to access corresponding Student .

Therefore, you should use (*iter)->Name (or (**iter).Name ) instead of iter->Name .