cannot get program to work can someone tell me what I am doing wrong

[C++ Programming]

/*
Name: Students Grades
Data: July 30, 2009
Description: This program is designed to compute and determine
the semester average, final letter grades,
class average and the distribution of the
student's letter grades of a given class.
In accomplishing the desired task, several
methods were used such as the trailer method,
calling a function and the return.
*/

# include
# include
# include

using namespace std;

int test1, test2, finalTest;
string studentName, letterGrade, printRecord;
float semesterAverage, finalLetterGrades, classAverage,
distributionOfLetterGrades;


int computerAverage (int ) {
int letterGrade (string)

ifstream inputfile;
inputfile. open (" StudentGrades.txt ");

ofstream ouputfile;
outputfile. open ("Roster.txt");

cout