Binary Search

I am trying to do a binary search for the following program.  This program reads a txt file and sorts and outputs the student information by either grade, email, last name, or first name.  
Using binary search my program is supposed to ask the user to enter a student grade, once the user enters the grade the program outputs the closes student name with grade.  For example, if user enters 86 for the grade the program should output Alice Keith has grade of 84.6.  

The infile has this information:
Richard,Jones,richars@jones.com,78.5
Alice,Keith,alicek@yahoo.com,84.6
Diego,Salazar,ds@hotmail.com,91.2
Max,Karlov,max@kkk.org,63.2

Here is my program.
#include <iostream>
#include <fstream>
#include <string>

using namespace std;

struct Student {
    string fname;
    string lname;
    string email;
    double grade;
};

Student* list[20];

int main1()
{
   
   
    fstream inFile("studentlist.txt");
    ofstream outFile;  //output file stream variable
      outFile.open("output10p1.txt"); //open outfile
   
      //declare variables
      char str[128];
    int i=0, c;            
   
    while (!inFile.eof())
    {
        inFile.getline(str, 128);
        string line = str;
        int pos1 = line.find(",");
        string fname = line.substr(0,pos1);
        int pos2 = line.find(",",pos1+1);
        string lname = line.substr(pos1+1,pos2-pos1-1);
        int pos3 = line.find(",",pos2+1);
        string email = line.substr(pos2+1,pos3-pos2-1);
        string grade = line.substr(pos3+1,line.length()-pos3-1);
        double grd = atof(grade.c_str());
         
        list[i] = new Student;
        list[i] ->fname = fname;
        list[i] ->lname = lname;
        list[i] ->email = email;
        list[i] ->grade = grd;
        i++;
   
    }
    // SAVE THE CURRENT VALUE OF THE LOOP COUNTER. IT'S THE STUDENTS COUNT
    int count = i;
                           
    // loop will keep function until user enters "0"
    while (true)
    {
        //(0 to quit)
        cout<<"Which column would you like to sort by (0 to quit) ==> "<<endl;
            cout<<"1) First Name"<<endl<<"2) Last Name"<<endl<<"3) Email"<<endl<<"4) Grade"<<endl;
        cin>>c;  
         
        // if "0" is entered loop will terminate
        if (c == 0)
            break;

        // Loop Runs Til Count == Number Of Students Read
        for (i=0; i < count; i++)
        {
            for (int j=i+1; j < count; j++)
            {
               
                switch (c)
                {
                case 1: if (list[i]->fname > list[j]->fname){
                    Student* tmp = list[i];
                    list[i] = list[j];
                    list[j] = tmp;
                    break;
                        }
                case 2: if (list[i]->lname > list[j]->lname){
                    Student* tmp = list[i];
                    list[i] = list[j];
                    list[j] = tmp;
                    break;
                        }
                case 3: if (list[i]->email > list[j]->email){
                    Student* tmp = list[i];
                    list[i] = list[j];
                    list[j] = tmp;
                    break;
                        }
                case 4: if (list[i]->grade > list[j]->grade){
                    Student* tmp = list[i];
                    list[i] = list[j];
                    list[j] = tmp;
                    break;
                        }
                   
                }
               
            }
           
        }
            cout <<"+-----------+-------------+---------------------+--------------------+"<<endl;
        cout <<"|First Name |  Last Name  |      Email          |      Grade         |"<<endl;
            cout <<"+-----------+-------------+---------------------+--------------------+"<<endl;
            
            // statement to output sorted table
        for (i=0; i< count; i++)
        {
                  cout <<list[i]->fname<<"\t    |   "<<list[i]->lname<<"\t  |  "<<list[i]->email<<"\t|\t"<<
                         list[i]->grade <<"\t     |"<< endl;
        }
            cout <<"+-----------+-------------+---------------------+--------------------+"<<endl;
      

      }
    return 0;
}