grader program

#include <cstdlib>
#include <iostream>
#include <fstream>
#include <string>
 
using namespace std;
 
void gradeInput()
{
    char grade;
    int f;
    float percent, testScore[3];
    string fname, lname, infoArray[4];
    cout << "\nplease enter in students' first name\n" << endl;
    cin >> fname;
    cout << "\nplease enter the students last name.\n" << endl;
    cin >> lname;
    ofstream inFile;
    inFile.open("students.txt", ios::app);
    cout << "\nplease enter in the test scores.\n" << endl;
    cin >> testScore[1];
    cin >> testScore[2];
    cin >> testScore[3];
    float myScore = testScore[1]+testScore[2]+testScore[3];
    percent = myScore/3;
    if (percent => 90)
    {
                grade = 'A';
    }
    else if (percent > 80 && percent < 90)
    {
         grade = 'B';
    }
    else if (percent > 70 && percent < 80)
    {
         grade = 'C';
    }
    else if (percent > 55 && percent < 70)
    {
         grade = 'D';
    }
    else if (percent <= 54)
    {
         grade = 'F';
    }
    inFile << lname <<", "<< fname << " - " << grade <<" /"<<  percent << "% " << endl;
    inFile.close();
}
 
void printGrades()
{
     system("cls");
     string student;
     ifstream outFile ("students.txt");
     while (outFile.good())
     {
           getline (outFile, student);
           cout << student << endl;
     }
     outFile.close();
}
void clear()
{
     system("cls");
     ofstream myClear;
     myClear.open("students.txt");
     myClear << "" << endl;
     myClear.close();
}
int main()
{
    int i = 5;
    string command;
    cout << "would you like to input or read student grades and information?" << endl;
    do{
       cin >> command;
       if (command == "input")
       {
                gradeInput();
       }
       else if (command == "read")
       {
             printGrades();
       }
       else if (command == "cleargrades")
       {
            clear();
       }     
       }while(i==5);
}
// output example: Harris, John - A / 95%