trouble making c++ student class [closed] - c++

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For my assignment I have to make a program to read student data from standard input, sort it by last name / first name, and print out the result to standard output. Students consists of a last name, first name, and a grade point average. It says to there are no more than 50 students.
It also says you should not rely on an external library function to do the sort.
Here is the example:
Ware Henry 87.2
Dantes Edmond 91.4
Earhart Amelia 92.6
Here is how it should be sorted:
Dantes Edmond 91.4
Earhart Amelia 92.6
Ware Henry 87.2
Here is the code I have so far that is not working properly:
#include <iostream>
#include <string>
using namespace std;
class student
{
public:
student();
void input();
void output();
void sort();
private:
string Fname;
string Lname;
float gpa;
}
student::student()
{
Fname = "";
Lname = "";
gpa = 0;
}
void student::input()
{
cout << "Enter first name, last name, and gpa"<<endl;
cin >> Fname >> Lname >> gpa;
}
void student::sort()
{
char temp;
int count = 0;
int i = 1;
while (i < word.size()) {
if (word[i - 1] > word[i]) {
temp = word[i];
word[i] = word[i + 1];
word[i + 1] = temp;
i++;
if (i >= word.size())
{
alpha(word);
}
}
else
{
count++;
}
}
return word;
}
void main()
{
student.input();
}
Any advice on where I went wrong and any possible solutions?

Answer 1

your student class has member variables to hold only one student, you need 50 instances of class student.
then you should hold these instances in an array/vector (whatever for container you are allowed to use) I assume you need to use a raw array so something like this will do.
student* students = new student[50];
what you then need is a compare function in your class to be able to sort the array, the compare function knows the internals of your class and you can decide how you want to sort the list e.g. after surname.
the sort function could be inside your class declared as a static function or maybe more logically an external function since student is not a container of student instances.
don't forget to delete the array when done
delete [] students;
in real world problems you would use std containers and e.g. algorithm sort for this kind of work.

Answer 2

Your compiler must have told you that word and alpha used in sort method are undeclared identifiers and count is assigned but never used.
Solution: Never ever steal code from wild wild web without understanding what it does. You may take others' code as inspiration, but blind copy-paste is a big no-no.
To give you a next step: you haven't even stored your students, you just input one, how would you sort just one entry? Think (and code) what you should use to store them and start working from there on how to sort them.
Good luck.

Answer 3

There are several reasons why your code is not working, first reason is that your class definition needs semicolon ';' at the end to close it.
class student
{
public:
student();
void input();
void output();
void sort();
private:
string Fname;
string Lname;
float gpa;
}; //semicolon here
In your sort() method the variable word is used but never declared, coding is not magic, the variable must declared and initialized before it is used like in your code.
while (i < word.size()) { //word must be declared somewhere
Also, in the sort method, you call a function alpha(word), this function does not exist in your program.
The sort method is of type void, which means it will not return anything, yet you are trying to return a string.
Another problem with the sort method is that it is never called from anywhere and will never be run.
There is also a big problem here with the way you are trying to use your class. To use the methods of the class you first have to instantiate an object of that class, you can then access the methods of the class through the object like this:
int main()
{
student theStudent;
theStudent;
theStudent.input();
return 0;
}
Another fundamental problem is that you are only going to get data for one object like this, you need to store several objects in something like an array and then sort the objects in the array:
int main()
{
student students[5];
for (int i = 0; i < 5; i++)
{
student newStudent;
students[i] = newStudent;
newStudent.input();
}
sort(students);
delete[] students;
return 0;
}
Which brings us to the sort method. It would be wise to not do the sorting as a method of the student class, but as a function called from main instead (like in the example above), that way it is easy to sort the array of student objects from main.
These are a few advice to start with, i am not going to do your complete homework for you though, if you use google and some of your precious energy, i believe that you will succeed.