selection sorting array of class objects

Question

i have a selection sort algorithm that partially works, i am using it to sort an array of class objects by age when it does this it sorts some of the contents correctly but fails to sort the first element. also is there a way to use the assignment operator for the class to make this a little easier.

thanks

below is my full code :

#include <iostream>
#include <string>
#include <math.h>

using namespace std;

void storeinfo() ;
void showinfo() ;
void menu() ;
void deleteinfo() ;
void displayallinfo() ;
void selectionSort() ;
int linsearch(string val) ;


class user 
{
    string firstname, lastname, currentteam, position, status ;
    int age ;
public:
    user() {};
    user(string fname, string lname, string cteam, string pos, string stat, int age) 
    {
        setFirstName(fname);
        setLastName(lname);
        setCurrentTeam(cteam);
        setPosition(pos);
        setStatus(stat);
        setAge(age);
    } ;



    user& operator = (const user& source)
    {
        firstname = source.firstname;
        lastname = source.lastname ;
        currentteam = source.currentteam ;
        position = source.position ;
        status = source.status ;
        age = source.age ;
    }


    void setFirstName(string fname)
        {firstname = fname;}
    void setLastName(string lname)
        {lastname = lname;}
    void setCurrentTeam(string cteam)
        {currentteam = cteam;}
    void setPosition(string pos)
        {position = pos;}
    void setStatus(string stat)
        {status = stat;}
    void setAge(int _age)
        {age = _age;}

    string getFirstName()
        {return firstname ;}
    string getLastName()
        {return lastname ;}
    string getCurrentTeam()
        {return currentteam ;}
    string getPosition()
        {return position ;}
    string getStatus()
        {return status ;}
    int getAge()
        {return age ;}
};

user player[20] ;
int arrlength = 3 ;

int main()
{
    menu() ;

    cin.get() ;
    return 0 ;
}

void storeinfo()
{
    string firstname ;
    string lastname ;
    string currentteam ;
    string position;
    string status ;
    int age ;

    for (int i=0; i < 3; i++)
    {
        cout << "\n\n Enter First Name : " ; 
        cin >> firstname ;
        player[i].setFirstName(firstname) ;
        cout << "Enter Last Name : " ; 
        cin >> lastname ;
        player[i].setLastName(lastname) ;
        cout << "Enter Player's Age : " ; 
        cin >> age;
        player[i].setAge(age) ;
        cout << "Enter Current Team : " ; 
        cin >> currentteam ;
        player[i].setCurrentTeam(currentteam) ;
        cout << "Enter Position : " ; 
        cin >> position ;
        player[i].setPosition(position) ;
        cout << "Enter Status : " ; 
        cin >> status ;
        player[i].setStatus(status) ;

        cout << "\n\n\n" ;
    }

    /*cout << string(50, '\n');*/

    menu() ;

}

void showinfo()
{
    string search;
    int found ;


    cout << "Please Enter The Player's Last Name : " ;
    cin >> search ;

    found=linsearch(search);

    if (found==-1)
    {
        cout << "\n There is no player called " << search ;
    }
    else
    {
        cout << "\n First Name : " << player[found].getFirstName() << "\n" << "Last Name : " << player[found].getLastName() <<
            "\n" << "Age : " << player[found].getAge() << "\n" << "Current Team : " << player[found].getCurrentTeam() << 
            "\n" << "Position : " << player[found].getPosition() << "\n" << "Status :  " << player[found].getStatus()  << "\n\n";
    }

    cin.get() ;

    menu() ;

}

void deleteinfo()
{
    int arrlength = 3 ;
    string search ;
    int found ;

    cout << "\n Delete A Player's Information \n\n" ;
    cout << "Please Enter The Player's Last Name : " ;
    cin >> search ;

        found=linsearch(search);

    if (found==-1)
    {
        cout << "\n There is no player called " << search ;
    }
    else
    {
        for (int i=found + 1; i < arrlength; ++i)
        {
            player[i-1].setFirstName(player[i].getFirstName()) ;
            player[i-1].setLastName(player[i].getLastName()) ;
            player[i-1].setAge(player[i].getAge()) ;
            player[i-1].setCurrentTeam(player[i].getCurrentTeam()) ;
            player[i-1].setPosition(player[i].getPosition()) ;
            player[i-1].setStatus(player[i].getStatus()) ;
        }

        --arrlength ;

        cout << "\n Player has been deleted." ;

        player[arrlength].setAge(0) ;
        player[arrlength].setCurrentTeam("") ;
        player[arrlength].setFirstName("") ;
        player[arrlength].setLastName("") ;
        player[arrlength].setPosition("") ;
        player[arrlength].setStatus("");
    }

    cin.get() ;

    menu() ;
}

void displayallinfo()
{

    selectionSort();

    for (int i=0; i < 3; i++)
    {
        cout << "\n First Name : " << player[i].getFirstName() << "\n" << "Last Name : " << player[i].getLastName() <<
            "\n" << "Age : " << player[i].getAge() << "\n" << "Current Team : " << player[i].getCurrentTeam() << 
            "\n" << "Position : " << player[i].getPosition() << "\n" << "Status :  " << player[i].getStatus()  << "\n\n";
    }

    cin.get() ;

    menu() ;
}

void menu()
{
    cout << "\n\n MENU" << "\n" ;
    cout << "\n A. Store Player Information" ;
    cout << "\n B. Show Player Informaton" ;
    cout << "\n C. Delete Player Information" ;
    cout << "\n D. Display All Players Sorted By Age";
    cout << "\n Z. Exit \n\n" ;

    string x =  "";
    cin >> x ;

    if (x=="a" | x=="A")
    { 
        storeinfo() ;
    }
    else if (x=="b" | x=="B")
    {
        showinfo() ;
    }
    else if (x=="c" | x=="C")
    {
        deleteinfo() ;
    }
    else if (x=="d" | x=="D")
    {
        displayallinfo() ;
    }
    else if (x=="z" | x=="Z")
    {
        exit(0) ;
    }
    else
    {
        cout << "Invalid Choice" ;
        menu() ;
    }
}

int linsearch(string val)
{
    for (int j=0; j <= 3; j++)
    {
        if  (player[j].getLastName()==val)
         return j ;         
    }
        return -1 ;
}

void selectionSort()
{
    int i, minIndex, minValue;
    for (i = 0; i < (arrlength - 1); i++)
    {
        minIndex = i ;
        minValue = player[i].getAge() ;
        for (int index = i + 1; index < arrlength; index++)
        {
            if (player[index].getAge() < minValue)
            {
                minValue = player[index].getAge();
                minIndex = index;

            }
        }

        player[minIndex].setAge(player[i].getAge());
        player[i].getAge() == minValue;

    }



}

Answer 1

Your "user" class is simple enough such that it doesn't need an overloaded assignment operator since all it's members are plain-old-data types or already have their own assignment operators (such as string). I would recommend removing the operator= method from this class so you don't have the upkeep of maintaining the operator= method when you add new members. C++ will automatically generate an assignment operator for your class if needed (that does memberwise assignment). You really only need an overloaded assignment operator when you have members that are pointers, but I digress.

Your selection sort function isn't actually sorting players. It's merely re-arranging the "age" value on each player. I think this is what you want to do to actually "sort" the "player" array. (Note this is more "C" that "C++", but bear with me).

void SimpleButSlowSort()
{
    bool fSorted = false;

    if (arrLength <= 1)
    {
       return;
    }

    while (fSorted)
    {
        fSorted = true;
        for (int index = 0; index < arrLength-1; index++)
        {
            if (player[index].getAge() > player[index+1].getAge())
            {
                user temp;
                temp = player[index];
                player[index] = player[index+1];
                player[index+1] = temp;
                fSorted = false;   
            }   
        }
    }
}

But if you want a more C++ standard way to sort, you can use the standard library for this. But that requires players to be in a type that can be iterated on. Example

bool MyPlayerCompare(user& u1, user& u2) { return (u1.getAge() < u2.getAge()); }
std::vector<user> players;
void FasterSort()
{
    std::sort(players.begin(), players.end(), MyPlayerCompare);

}