Trying to build a student grading array program

Your code, despite its formatting, works well against the example output. Assuming this is a homework assignment, you may not find all of this useful or even understandable at first. Since I've already started this, I'll keep the general idea the same. This code mostly serves to "replace" your multi-dimensional arrays, though I understand that you may need to keep them. Other than that, this is one way of improving your program.

• Try not to use using namespace std. Read this for more information.

• void main() may compile for you, but it's very wrong for main() in particular. It should be int main() instead. More information here.

• Also try not to use system("PAUSE"). If you cannot set your IDE to pause, you may call std::cin.get() instead.

• Although you're just trying this for a set number of students, I would recommend an std::vector of std::vectors (for adding any number of students and any number of tests). In order to use this, include <vector>. Your typedefs and function prototypes could then look like this:

  // rename these types for less typing later on
  typedef std::vector<double> NumVect;
  typedef std::vector<NumVect > VectOfNumVects;
  typedef std::pair<double, char> NumCharPair; // include <utility>
  
  VectOfNumVects getGrades(unsigned, unsigned); // new function
  NumCharPair calcTestAvg(const NumVect&); // new function
  void displayGrades(const VectOfNumVects&);
  

• Your main() could then look like this:

  int main()
  {
      // get the number of students (4 for you)
      std::cout << "Number of students: ";
      unsigned numStudents;
      std::cin >> numStudents;
  
      // get the number of tests (3 for you)
      std::cout << "Number of tests: ";
      unsigned numTests;
      std::cin >> numTests;
  
      // get the grades and then display them
      VectOfNumVects grades = getGrades(numStudents, numTests);
      displayGrades(grades);
  }
  

• getGrades():

  VectOfNumVects getGrades(unsigned numStudents, unsigned numTests)
  {
      VectOfNumVects students; // new "student" vector
  
      // get tests for each student
      for (unsigned i = 0; i < numStudents; ++i)
      {
           NumVect tests; // new "test" vector within "student" vector
           std::cout << "Student " << i+1;
  
           // get each test grade for current student
           for (unsigned j = 0; j < numTests; ++j)
           {
               std::cout << " test " << j+1 << " grade: ";
               double testGrade;
               std::cin >> testGrade;
               tests.push_back(testGrade);
           }
  
           students.push_back(tests);
      }
  
      return students;
  }
  

• calcTestAvg():

  NumCharPair calcTestAvg(const NumVect &tests)
  {
      // new std::pair here for storing the average with its letter grade
      // first item is the average and second is the letter grade
      // first initialized with 0 average and "blank" grade
      NumCharPair avgPair = std::make_pair(0.0, ' ');
  
      // add up total test grades, then calculate average
      for (unsigned t = 0; t < tests.size(); ++t)
      {
          avgPair.first += tests[t];
      }
  
      avgPair.first /= tests.size();
  
      // determine the letter grade based on average
      if (avgPair.first >= 90)
          avgPair.second = 'A';
      else if (avgPair.first < 90 && avgPair.first >= 80)
         avgPair.second = 'B';
      else if (avgPair.first < 80 && avgPair.first >= 70)
          avgPair.second = 'C';
      else if (avgPair.first < 70)
          avgPair.second = 'F';
  
      return avgPair;
  }
  

• displayGrades():

  // This won't display your desired output,
  // but you could always tweak the code however you please
  
  void displayGrades(const VectOfNumVects &students)
  {
      for (unsigned s = 0; s < students.size(); ++s)
      {
          std::cout << "Student " << s+1 << ": \n";
  
          for (unsigned t = 0; t < students[s].size(); ++t)
          {
              std::cout << "\nTest " << t+1 << ": " << students[s][t]; 
          }
  
          // get and display student average with respective letter grade
          NumCharPair result = calcTestAvg(students[s]);
          std::cout << "\n\nAverage: " << result.first;
          std::cout << "\nLetter grade: " << result.second;
      }
  }
  

I'm assuming you don't know what the previous commenter is talking about when he mentions "vectors." You're probably a beginner, right? Then I wouldn't worry about vectors for a little bit.

• On returning an average:

What have you tried? Show us an attempt, and we can help you. But each row is a student, right? So to get a single student's average, just take the average the value in every column for that single row. If you want the student in row 0, it'd be like

int student = 0;
int sum = 0;
for(int i = 0; i < MAX_NUM_OF_COLUMNS; i++){
sum += gradeArray[student][i];
}
average = sum / MAX_NUM_OF_COLUMNS;

To convert that into a grade wouldn't be very complicated. Give it a try, and we'll help you with what you come up with.