Need help sorting the array alphabetically

Question

I have to sort the last names in alphabetical order and I have been looking for hours on how to do this but my book which is garbage offers no examples other than integers so any help will be awesome. Here is my code:

#include <cstdlib>
#include <iostream>
#include <iomanip>


using namespace std;

int getAverage(int,int,int);
string letterGrade(int);
void getInfo();

 int main(int argc, char *argv[])
{
getInfo();
system("PAUSE");
return EXIT_SUCCESS;
}

void getInfo()
{
const int info = 5;
string last[info];
string first[info];
int ID[info];
int score1[info];
int score2[info];
int score3[info];

for (int count = 0; count < info; count++)
    {
         cout << "last name\n";
         cin >> last[count];
         cout << "first name\n";
         cin >> first[count];
         cout << "enter ID\n";
         cin >> ID[count];
         cout << "enter test 1\n";
         cin >> score1[count];
         cout << "enter test 2\n";
         cin >> score2[count];
         cout << "enter test 3\n";
         cin >> score3[count];

    }

    cout << endl;

    for (int count = 0; count < info; count++)
    {

     cout << last[count] 
     << setw(10) << first[count] 
     << setw(10) << ID[count] 
     << setw(10) <<score1[count]
     << setw(10) << score2[count] 
     << setw(10) << score3[count] 
     << setw(10) << getAverage(score1[count],score2[count],score3[count])
     << setw(10) <<  letterGrade(getAverage(score1[count],score2[count],score3[count]));


        cout << endl;
    }

}
string letterGrade(int average)
{
   string lGrade;

    if (average > 89)
        lGrade = "A";
    else if (average > 79 && average < 90)
        lGrade = "B";
    else if (average > 69 && average < 80)
        lGrade = "C";
    else if (average > 59 && average < 70)
        lGrade = "D";
    else if (average >= 0 && average < 60)
        lGrade = "F";
    return lGrade;
}
int getAverage(int score1,int score2,int score3)
{
 int average;
 average = ((score1 + score2 + score3)/ 3);
 return average;
}

Answer 1

I would suggest using struct i/o a bunch of arrays and std::sort (assuming you are allowed to do that).

#include <cstdlib>
#include <iostream>
#include <iomanip>
#include <algorithm>
#include <vector>


using namespace std;

int getAverage(int,int,int);
string letterGrade(int);
void getInfo();

struct gradeInfo {
    string last;
    string first;
    int ID;
    int score1;
    int score2;
    int score3;
};

bool mySort (gradeInfo g1,gradeInfo g2) { 
    return (g1.last <g2.last); 
} //lexicographical string comparison

 int main(int argc, char *argv[])
{
getInfo();
system("PAUSE");
return EXIT_SUCCESS;
}

void getInfo()
{
const int info = 5;
vector<gradeInfo> grades;

for (int count = 0; count < info; count++)
    {
         gradeInfo gradesEntry;
         cout << "last name\n";
         cin >> gradesEntry.last;
         cout << "first name\n";
         cin >> gradesEntry.first;
         cout << "enter ID\n";
         cin >> gradesEntry.ID;
         cout << "enter test 1\n";
         cin >> gradesEntry.score1;
         cout << "enter test 2\n";
         cin >> gradesEntry.score2;
         cout << "enter test 3\n";
         cin >> gradesEntry.score3;
         grades.push_back(gradesEntry);
    }

    cout << endl;

    sort(grades.begin(), grades.end(), mySort);

    for (int count = 0; count < info; count++)
    {
     int average = getAverage(grades[count].score1,grades[count].score2,grades[count].score3);
     cout << grades[count].last 
     << setw(10) << grades[count].first 
     << setw(10) << grades[count].ID 
     << setw(10) << grades[count].score1
     << setw(10) << grades[count].score2 
     << setw(10) << grades[count].score3
     << setw(10) << average
     << setw(10) <<  letterGrade(average);


        cout << endl;
    }

}
string letterGrade(int average)
{
   string lGrade;

    if (average > 89)
        lGrade = "A";
    else if (average > 79 && average < 90)
        lGrade = "B";
    else if (average > 69 && average < 80)
        lGrade = "C";
    else if (average > 59 && average < 70)
        lGrade = "D";
    else if (average >= 0 && average < 60)
        lGrade = "F";
    return lGrade;
}
int getAverage(int score1,int score2,int score3)
{
 int average;
 average = ((score1 + score2 + score3)/ 3);
 return average;
}