rfind function with files help

[rcflores]

I'm having trouble taking a students name from a file putting it into a string and cutting the string into first and last name. For this assignment I have to use the rfind function and a struct. Any help would be appreciated

Heres my code so far

#include<iostream>
#include<string>
#include<fstream>
#include<iomanip>
#include <cstddef>
using namespace std;

//Struct to show student types
struct studentType
{
	string str;
	string key = (" ");int found = str.rfind(key);
	string studentFName = str.substr(0, found); //students first name
	string studentLName = str.substr(found + 1);// students last name
	
	double testScore; //students test score
	char grade; //students grade
};


int main()
{
	int c = 0;
	double highestTestScore = 0;
	
	string fname = " ";
	string lname = " ";

	
	
	studentType students[20];
	ifstream inFile;
	
	inFile.open("student.dat", ios::in);
	if (inFile.is_open())
	{
				
		while (!inFile.eof())
		{
		    getline(inFile, students[c].str);
			inFile >> students[c].testScore;
			inFile.ignore(100, '\n');
			
			
			c++;
		}
		//if else statement for letter grade
		for (int c = 0; c < 6; c++)
		{

			if (students[c].testScore>=90 && students[c].testScore <= 100)
				students[c].grade = 'A';
			else if (students[c].testScore >= 80 && students[c].testScore <= 89)
				students[c].grade = 'B';
			else if (students[c].testScore >= 70 && students[c].testScore <= 79)
				students[c].grade = 'C';
			else if (students[c].testScore >= 60 && students[c].testScore <= 69)
				students[c].grade = 'D';
			else
				students[c].grade = 'F';

			//if statement to get the students highest grade
			if (students[c].testScore > highestTestScore)
			{
				highestTestScore = students[c].testScore;
				fname = students[c].studentFName;
				lname = students[c].studentLName;
			}
		}
		cout << left << fixed;
		cout << setw(15) << "Last Name";
		cout << setw(15) << "First Name";
		cout << setw(15) << "Test Score";
		cout << setw(15) << "Grade" << endl;
		
		//for loop for students
		for (int i = 0; i < 6; i++)
		{
			cout << setw(15) << students[i].studentLName; //supposed to display last name
			cout << setw(15) << students[i].studentFName; //supposed to display first name
			cout << setw(15) << setprecision(1)<<students[i].testScore;
			cout << setw(15) << students[i].grade << endl;
			
		}
		inFile.close();
		
	}
	else
	{
		cout << "Error Openning file" << endl;
	}

	cout << endl << "Highest test score: " << highestTestScore;
	cout << " Student name: " << fname << " "<<lname<< endl;
	
	
	system("pause");
	return 0;

}