I'm having some problems working a assignment I'm working on. It doesn't work!
The program is suppose to output a letter grade given a student's test score. There is a main function and four functions for the four subtasks. Here the code. Thank you very much for your help! 
#include <iostream>
#include <conio.h>
using namespace std;
void GetScore(double score);
//Purpose: This function asks the user to enter a score between 0 and 100
// inclusive. If the score is not between the two values then print
// an error message and ask for another score.
//
// Precondition:
// None
// Postcondition:
// The value of number has been set to an integer between 1 and 100 inclusive
//------------------------------------------------------------------------------
void DetermineGrade(double score, char grade);
//Purpose: This function determines the score and displays the grade for the
// value.
//
//Precondition:
// Grade is assigned.
//Postcondition:
// The score will determine and grade will be diplayed.
//------------------------------------------------------------------------------
void PrintGrade(double score, char grade);
//Purpose: This function prints the grade and score.
//
//Precondition:
//
//Postcondition:
//
//------------------------------------------------------------------------------
//void GetResponse(char response);
//Purpose: This function will ask whether they want to continue or not.
//
//Precondition:
//
//Postcondition:
//
//------------------------------------------------------------------------------
int main()
{
double score;
char grade;
GetScore( score);
cout << "Please enter your score between 0 and 100 ";
cin >> score;
getch();
return 0;
}
//------------------------------------------------------------------------------
void GetScore(double score)
{
cout << "Please enter your score between 0 and 100 ";
cin >> score;
while ((score < 0) || (score > 100))
{
cout << "The score is: " << score << " is not between 1 and 100 inclusive.\n";
cout << "Try again. Enter a score between 1 and 100: ";
cin >> score;
}
}
void DetermineGrade(double score, char grade)
{
if (score >= 85)
grade = 'A';
else if (score >= 70)
grade = 'B';
else if (score >= 60)
grade = 'C';
else if (score >= 50)
grade = 'D';
else
grade = 'F';
}
void PrintGrade(double score, char grade)
{
cout << "The score is: " << score << endl;
cout << "The grade is: " << grade << endl;
}
#include <iostream>
#include <conio.h>
using namespace std;
void GetScore(double score);
//Purpose: This function asks the user to enter a score between 0 and 100
// inclusive. If the score is not between the two values then print
// an error message and ask for another score.
//
// Precondition:
// None
// Postcondition:
// The value of number has been set to an integer between 1 and 100 inclusive
//------------------------------------------------------------------------------
void DetermineGrade(double score, char grade);
//Purpose: This function determines the score and displays the grade for the
// value.
//
//Precondition:
// Grade is assigned.
//Postcondition:
// The score will determine and grade will be diplayed.
//------------------------------------------------------------------------------
void PrintGrade(double score, char grade);
//Purpose: This function prints the grade and score.
//
//Precondition:
//
//Postcondition:
//
//------------------------------------------------------------------------------
//void GetResponse(char response);
//Purpose: This function will ask whether they want to continue or not.
//
//Precondition:
//
//Postcondition:
//
//------------------------------------------------------------------------------
int main()
{
double score;
char grade;
GetScore( score);
cout << "Please enter your score between 0 and 100 ";
cin >> score;
getch();
return 0;
}
//------------------------------------------------------------------------------
void GetScore(double score)
{
cout << "Please enter your score between 0 and 100 ";
cin >> score;
while ((score < 0) || (score > 100))
{
cout << "The score is: " << score << " is not between 1 and 100 inclusive.\n";
cout << "Try again. Enter a score between 1 and 100: ";
cin >> score;
}
}
void DetermineGrade(double score, char grade)
{
if (score >= 85)
grade = 'A';
else if (score >= 70)
grade = 'B';
else if (score >= 60)
grade = 'C';
else if (score >= 50)
grade = 'D';
else
grade = 'F';
}
void PrintGrade(double score, char grade)
{
cout << "The score is: " << score << endl;
cout << "The grade is: " << grade << endl;
}