how to sort an integer that is declared in the private

Question

I declared the int id in the private, part of my class.

                    private:
                      int id,age;
                      float gpa;
                      string last,first;

This code is in my file to display and call for functions that are in the array, and to sort the int id.

        student[i].sort_array(student[i].id,cap);
        i++;
        cout << i;

This is in a seperate file where i put my functions, i am able to display the contents of the array, if i student[i].put(cout) the data. I am not sure how to pass in an integer that would be in the provate part of my class

        void student::sort_array(int student[i].get(id),int n)
        {

            int j,temp;
            for(j=0;j<n-1;j++)
            { 
         //if out of position switch the out of align number
            if(student[j]<student[j+1])
            {
            temp =  student[j];
            student[j] = student[j+1];
            student[j+1] = temp;
            }
         }

`void student::sort_array(int student[i].get(id),int n)` doesn't make any sense. — johnsyweb, May 01 '12 at 10:40
`.sort_array` shouldn't be a member of one specific student. — MSalters, May 01 '12 at 10:41
I am trying to teach myself programming, by making a program for school. — MIkey27, May 01 '12 at 10:46

score 3 · Answer 1 · answered May 01 '12 at 10:42

3

The normal method is to have a bool student::compareAges(Student const& otherStudent) method, aand pass that as an extra argument to your comparison function. E.g. it's the third argument to std::sort when you're not using the default operator<

answered May 01 '12 at 10:42

MSalters

173,980
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350

1

Indeed, although to fit the question I'd say it should be `student::compareIDs`. The point being that you teach `Student` how to compare itself to another `Student` so your sorting code doesn't have to know about any internal details. – Matthew Walton May 01 '12 at 10:47

score 0 · Answer 2 · answered May 01 '12 at 10:42

0

The sort_array function must not be in a different file but in the .cpp of your Student class decleration.

And you do not have to pass the id as a parameter since you can access (even if it is private) it because you will be in that class's scope.

answered May 01 '12 at 10:42

phantasmagoria

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score 0 · Answer 3 · edited May 23 '17 at 11:49

sort_array doesn't belong in the student class! Nor does it make sense "to sort the int id" for an instance of student.

Sorting a collection of students by id using the C++ standard library's std::sort() function is certainly possible.

You can define a less-than operator for your student class, thus:

bool student::operator <(student const& rhs) const
{
    return id < rhs.id;
}

Since it is a member of the class it can access all of its data.

It must be public:, then std::sort() function will be able to use this to sort a standard C++ container (or array) of student. based on the id. If you want to compare multiple attributes of the class, be sure to implement strict weak ordering.

how to sort an integer that is declared in the private

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