How do I rewrite loop to use mapped array C++

Question

0.00/5 (No votes)

See more:

The array is set up using:

C++

class Roster {
public:
	void add(string studentID, string firstName, string lastName, string email, int age, int daysInCourse1, int daysInCourse2, int daysInCourse3, Degree degreeProgram);
	void printAll();
	void printByDegreeProgram(int degreeProgram);
	void printDaysInCourse(string studentID);
	void printInvalidEmails();
	void remove(string studentID);
	~Roster();
	std::map<string, shared_ptr<Student> > classRosterArray;
};

void Roster::printAll()
{
    for (int i = 0; i < sizeof(classRosterArray) / sizeof(classRosterArray[i]); i++) {
        classRosterArray[i]->print();
    }
}

void Roster::printByDegreeProgram(int degreeProgram)
{
    for (int i = 0; i < sizeof(classRosterArray) / sizeof(classRosterArray[i]); i++) {
        if (classRosterArray[i]->fetchDegreeProgram() == degreeProgram) {
            classRosterArray[i]->print();
        }
    }
}

void Roster::printDaysInCourse(string studentID)
{
    float avg = 0;
    int max = 3;
    for (int i = 0; i < sizeof(classRosterArray) / sizeof(classRosterArray[i]); i++) {
        if (classRosterArray[i] != nullptr && classRosterArray[i]->fetchStudentId() == studentID) {
            int *daysInCourse = classRosterArray[i]->fetchDaysInCourse();
            for (int x = 0; x < max; x++) {
                avg += daysInCourse[x];
            }

            cout << "Student " << classRosterArray[i]->fetchStudentId() << "'s average number of days in each course is." << (avg / max) << "\n";
            break;
        }
    }
}

void Roster::printInvalidEmails()
{
    for (int i = 0; i < sizeof(classRosterArray) / sizeof(classRosterArray[i]); i++) {
        string email = classRosterArray[email]->fetchEmail();
        bool isValid = false;

        size_t found = email.find("@");
        if (found != string::npos) {
            found = email.find(".");
            if (found != string::npos) {
                found = email.find(" ");
                if (found == string::npos) {
                    isValid = true;
                }
            }
        }

        if (!isValid) {
            cout << email << " is not a valid email address \n";
        }
    }
}

What I have tried:

This was originally set up as an array initialized with nullptrs that does not work in C++ as it turns out for direct comparison loops. So on the advice of someone, I switched to the map which fixed one of my problems but broke the classarray loops later on and I am not sure exactly how to rewrite these to compensate.

Any help you guys can provide would be greatly appreciated

Posted 28-Nov-18 9:37am

gtyoung2

Updated 28-Nov-18 16:31pm

v2

Add a Solution

Comments

jeron1 28-Nov-18 16:55pm

something like?

for (int i = 0; i < classRosterArray.size(); i++)
{...
}

or try iterators, something like,

for (std::map::iterator it = classRosterArray.begin(); it != classRosterArray.end(); ++it)
{
...
}

1 solution

Add a Solution

Add your solution here

Treat my content as plain text, not as HTML

Preview 0

…

Existing Members

Sign in to your account

...or Join us

Download, Vote, Comment, Publish.

Your Email
Password
Forgot your password?

Your Email
This email is in use. Do you need your password?
Optional Password

I have read and agree to the Terms of Service and Privacy Policy
Please subscribe me to the CodeProject newsletters

When answering a question please:

Read the question carefully.
Understand that English isn't everyone's first language so be lenient of bad spelling and grammar.
If a question is poorly phrased then either ask for clarification, ignore it, or edit the question and fix the problem. Insults are not welcome.
Don't tell someone to read the manual. Chances are they have and don't get it. Provide an answer or move on to the next question.

Let's work to help developers, not make them feel stupid.

This content, along with any associated source code and files, is licensed under The Code Project Open License (CPOL)

David O'Neil · Answer 1 · 2018-11-28T16:31:00

Something like this:

C++

void Roster::printDaysInCourse(string studentID)
{
    float avg = 0;
    int max = 3;
    for (auto it : classRosterArray) {
      int *daysInCourse = it->second->fetchDaysInCourse();
      for (int x = 0; x < max; x++) {
         avg += daysInCourse[x];
      }
      cout << "Student " << it->second->fetchStudentId() << "'s average number of days in each course is." << (avg / max) << "\n";
   }
}

But you have a design problem in that you can't have two students with the same name in your roster. If you insist on a map, put the student ID as the key, instead of the value (

std::map<shared_ptr<Student>, string> classRosterArray;

). That overcomes the problem. But I'd recommend using a vector of shared_ptrs, or unique_ptrs, instead of an array or a map, because you don't have to use the 'first' and 'second' nomenclature. You can also go back to something closer to your original design and overcome the lack of duplicate names issue. You will have to learn how to use vectors, though, and revamp your Roster class to add and remove from the vector properly.