Array sorting error

Problem of sorting the ID in int main.
anyone know how to fix the code ?
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

#include<iostream>
#include<string>
#define MAX 6
#define size 10

using namespace std;

struct student {
string name;
int id;
string prog;
double cgpa;
};


class stinfo {
    private:
        student data[size];
        int last;
    public:
        stinfo();
        void add(string name, int id, string prog, double cgpa);
        void selectionSort(int A[]);
        void printAll(int count);

};


int min(int a[], int pos){
    int min=99999;
    int i;
    int c;
    for(i =pos; i<MAX;i++){
        if(a[i]<min){
            min=a[i];
            c=i;
        }
    }
    return c;
}


stinfo :: stinfo()
{
    last = 0 ;
}



void stinfo::add(string name, int id,string prog, double cgpa)
{
    if (last == size) {
    return ;
}
data[last].name = name;
data[last].id = id;
data[last].prog = prog;
data[last].cgpa = cgpa;
++last;
}           // all infomation are in data 


void stinfo::selectionSort(int data[]) 
{

    int i,j, temp;
     for (i=0; i<MAX; i++)
     {
         j = min(data,i);
         if(data[j]<data[i])
         {
            temp = data[j];
            data[j] = data[i];
            data[i] = temp;
         }       
    }
}


void stinfo::printAll(int count)
{
    if (last == size){
        return ;
    }else{

        for (int i =0; i<count; i++)
        {
            cout<<data[i].name<<endl
                <<data[i].id<<endl
                <<data[i].prog<<endl
                <<data[i].cgpa<<endl;
        }

    }
}



int main()
{

    char ans;
    string name1,prog1;
    int id1;
    double cgpa1;
    int count = 0;

    stinfo st;

    do{


    cout <<"A.) Insert NEW Student Record."<<endl
         <<"B.) print all Student Record."<<endl
         <<"C.) Sorting."<<endl;


    cout <<"Please Choice ONE Option : ";
    cin >>ans;
    cout<<endl;

    switch ( ans )
    {
    case 'a':
    case 'A':
        cout <<endl;
        cout <<">>>>> INSERT NEW STUDENT INFORMATION <<<<<"<<endl;

        cout <<"NAME : ";
        cin >>name1;

        cout <<"ID: ";
        cin >>id1;

        cout <<"PROGRAMME : ";
        cin >>prog1;

        cout <<"CGPA: ";
        cin >>cgpa1;

        st.add ( name1,id1,prog1,cgpa1 );

        cout <<endl
             <<"INSERT COMPLETE... "<<endl
             <<endl;
        count ++;
        break;

    case 'b':

        st.printAll(count);
        break;

    case 'c':

    st.selectionSort(st.data);

    for (int i=0; i<MAX; i++)
    cout<<a[i]<<endl;


    break;

        default :
        cout <<"Please Try Again..."<<endl
             <<endl;
    }

    }while ( toupper(ans) !='F' ) ;

        cout <<"EXIT The Program..."<<endl
             <<endl;

    system("pause");
    return 0;

}