Having trouble iterating through a vector in C++

Question

I have been trying to code a program where I input data for a student class(with (const string &first_name, const string &last_name, float gpa, int id), that can display which students have a gpa above 1.00. I am having trouble iterating through a vector. Here is the function causing me trouble:

vector<Student> find_failing_students(vector<Student> &students) {
    vector<Student> failing_students;
    int endVar;
    vector<Student>::iterator it;
    std::vector<Student>::iterator &forwardmarch = &students.begin();

    while(forwardmarch != &students.end())
    {
        Student temp = Student(forwardmarch->first_, forwardmarch->last_, forwardmarch->gpa_, forwardmarch->id_);
        if(temp.getgpa(temp) < 1) {
                    failing_students.push_back(temp);
        forwardmarch++;
    }

the std::vector<Student>::iterator &forwardmarch = &students.begin(); part is giving me the following error: invalid initialization of non-const reference of type 'std::vector::iterator&' {aka '__gnu_cxx::__normal_iterator >&'} from an rvalue of type 'std::vector::iterator*' {aka '__gnu_cxx::__normal_iterator >*'}

the while loop while(forwardmarch != &students.end()) also gives me the following error: no match for 'operator!=' (operand types are 'std::vector::iterator' {aka '__gnu_cxx::__normal_iterator >'} and 'std::vector::iterator*' {aka '__gnu_cxx::__normal_iterator >*'})

I have tried many things and also tried using a more typical for loop too, one like

for(std::vector<T>::iterator it = v.begin(); it != v.end(); ++it) {
    it->doSomething();
 }

Im a little confused and am pretty new to C++, any help would be appreciated. Thanks!

Answer 1

This line makes no sense:

std::vector<Student>::iterator &forwardmarch = &students.begin();

On the left side, the ampersand tells that you are declaring an object reference (not an object). On the right side, the ampersand tells to obtain a pointer to the object, instead of the object itself. The correct use is to declare a new object and assign it directly:

std::vector<Student>::iterator forwardmarch = students.begin();

This is very fundamental stuff. The reading topic would be pointers and references in C++.