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C++ containair

Discussion in 'C++' started by pap, Mar 24, 2012.

  1. pap

    pap New Member

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    Hi, I would like to get some help with this program


    I am trying to implement a student grading system.
    -Use an Associative container, multimap.
    -Search record by Student name (the key) and the data consists of student ID and GPA.
    Since more than one student can have the same name, use
    multimap.

    progam does the following:
    1. It will use a multimap as the container.
    2. It will use the Student class to describe the
    ID and GPA. multimap will be declared:
    multimap<string, Student> grades;
    3. use data(names, IDs and GPAs)
    4. The main() driver will display a menu of commands available to
    the user: The commands are:
    a. insert a student’s data into the system, The program will
    allow duplicate names to be inserted.
    b. Find a student’s data, given the student’s name(key). If
    there are multiple students in the container with the given
    name, display information about all of them.
    c.. Exit the system

    d. it should have files (.h and .cpp)
     
  2. dearvivekkumar

    dearvivekkumar New Member

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    std::map<string, Student>
    Key must always be unique!
     
  3. pap

    pap New Member

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    I need help to implement this program using "Multimap", my code bellow is using "map", i want to convert it into MultiMap. thanks
    Code:
    #include <iostream>
    #include <string>
    #include <map>
    using namespace std;
    
    class Student
    {
    public:
      //--- Constructor
      Student (int id = 0, double gpa = 0);
      //--- Output operator
      friend ostream & operator<<(ostream & out, const Student & s);
      //--- Input operator
      friend istream & operator>>(istream & in, Student & s);
      //--- Less-than operator
      friend bool operator<(const Student & a, const Student & b);
    private:
      //--- Data members
      int myId;
      double myGPA;
    };  // end of class Student
    
    //--- Definition of constructor
    inline Student::Student(int id, double gpa)
      : myId(id), myGPA(gpa)
    { }
    
    //--- Definition of input operator
    inline istream & operator>>(istream & in, Student & s)
    {
      in >> s.myId >> s.myGPA;
    return in;
    }
    
    //--- Definition of output operator
    inline ostream & operator<<(ostream & out, const Student & s)
    { out << "id = " << s.myId << "  GPA = " << s.myGPA;
     return out;
    }
    
    //--- Definition of less-than operator
    inline bool operator<(const Student & a, const Student & b)
    { return a.myId < b.myId; }
    
    //==================================================================
    
    int main()
    {
      typedef map<string, Student, less<string> > map1;
      typedef map<Student, string, less<Student> > map2;
    
      map1 a1;   // associative array of Student, index type is string
      map2 a2;   // associative array of string, index type is Student
    
      Student s;
      s = Student(12345, 3.3);  a1["Fred"] = s;   a2[s] = "Fred";
      s = Student(32322, 3.9);  a1["Al"] = s;     a2[s] = "Al";
      s = Student(13131, 2.5);  a1["Joan"] = s;   a2[s] = "Joan";
      s = Student(22121, 4.0);  a1["Barb"] = s;   a2[s] = "Barb";
      s = Student(28888, 2.9);  a1["George"] = s; a2[s] = "George";
      s = Student(19981, 3.0);  a1["Dot"] = s;    a2[s] = "Dot";
      s = Student(20012, 2.9);  a1["Sue"] = s;    a2[s] = "Sue";
      string name;
      cout << "Enter a name: ";
      cin >> name;
      map1::iterator it1 = a1.find(name);
      cout << name << " has ";
      if (it1 == a1.end())
        cout << "no info";
      else
        cout << a1[name];
      cout << endl;
    
      Student aStudent;
      cout << "Enter a Student's id and GPA: ";
      cin >> aStudent;
      map2::iterator it2 = a2.find(aStudent);
      cout << "Student " << aStudent << " is ";
    
      if (it2 == a2.end())
        cout << "no info";
      else
        cout << a2[aStudent];
      cout << endl;
    }
     
    Last edited by a moderator: Mar 27, 2012

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