How to create an iterator function - c++

Question

So my task is to create a function with signature: list<Person>::iterator SearchPos(list<Person> &Mylist, Person &person). Which would later get the appropraite position for the person, in order of birth, to be inserted into the list. Its return type should be an Iterator.
I have tried doing the following :
list<Person>::iterator SearchPos(list<Person> &MyList, Person &person)
{
}
int main()
{
char Dot;
string Dummy;
string Name;
int Day, Month, Year;
fstream MyFile;
MyFile.open("Kontakte.txt");
list<Person> BirthdayList; // Creating list of type Person
if(MyFile.is_open()) {cout << "File opened successfully." << endl;};
getline(MyFile, Name, ','); //Get line until "," is reached
MyFile >> Day >> Dot;
MyFile >> Month >> Dot;
MyFile >> Year;
getline(MyFile, Dummy); //Gets rid of \n char.
Person P1 (Name, Day, Month, Year);
SearchPos(&BirthdayList, &P1);
but even without the body of SearchPos() function I get the error :
invalid initialization of non-const reference of type 'std::__cxx11::list<Person>&' from an rvalue of type 'std::__cxx11::list<Person>*'|
Edit
Thanks a lot for the help with that error message it would take me embarrasingly long to figure that one out. The answer to my orginal question is as follows
list<Person>::iterator SearchPos(list<Person> &MyList, Person &person)
{
list<Person>::iterator pos;
//body of the function
return pos;
}
This will make the function return an iterator as wanted by my task.

Answer 1

After some getting used to, the compiler error is actually clear. Maybe this will help you to decipher it.
invalid initialization of non-const reference of type 'std::__cxx11::list&' from an rvalue of type 'std::__cxx11::list*'|
std::__cxx11::list<Person> is actually list<Person> in your code. The standard library just adds some namespaces. Maybe if we switch the example to int, it is clearer.
int SearchPos(int& index){} // let's define a function taking a reference to `int`.
int main() {
int my_index;
SearchPos(&my_index);
}
would similarly result in
invalid initialization of non-const reference of type 'int&' from an rvalue of type 'int*'|
So the problem is that you cannot convert int* to int&.
Why? Well, they are different types, and you cannot convert between them.
Where is int* coming from? You are getting the type int*, since the operator & returns an address to the int, thus a pointer to int (int*). (extra, the returned address is a rvalue, since it itself does not have an address.)
So either you make sure that the type you are inputting corresponds to the signature of the method:
int SearchPos(int* index){}
int main() {
int my_index;
SearchPos(&my_index);
}
, or, what you should do, since the signature is set, you make sure you pass a reference:
int SearchPos(int& index){}
int main() {
int my_index;
SearchPos(my_index);
}

Answer 2

You need to call the function like this:
SearchPos(BirthdayList, P1);
As mentioned in the comments you were passing the parameters as pointers when your function was looking for a reference. Using the ampersand (&) returns a pointer to your object. I know it may be confusing and seem like you need to pass in the address since your function accepts a reference but you don't need to do that. Declaring it as a reference in the function parameters is all you need to do.