Will they be considered magic numbers?

Question

I just finished writing a program for a programming class, and I want to avoid using magic numbers, so here is my question:

In the function below, are my array indices considered magic numbers?

the code:

string CalcGrade(int s1, int s2, int s3, double median)
{
const int SIZE = 23;
const int LETTER_GRADE_BARRIERS[SIZE] = { 400, 381, 380, 361, 360, 341, 340, 321, 320, 301, 300, 281, 280, 261, 260, 241, 240, 221, 220, 201, 200, 181, 180 }; 
double finalGrade;
string letterGrade;

finalGrade = s1 + s2 + s3 + median;

if (finalGrade >= LETTER_GRADE_BARRIERS[1] && finalGrade <= LETTER_GRADE_BARRIERS[0])
{
    letterGrade = "A";
}
else if (finalGrade >= LETTER_GRADE_BARRIERS[3] && finalGrade <= LETTER_GRADE_BARRIERS[2])
{
    letterGrade = "A-";
}
else if (finalGrade >= LETTER_GRADE_BARRIERS[5] && finalGrade <= LETTER_GRADE_BARRIERS[4])
{
    letterGrade = "B+";
}
else if (finalGrade >= LETTER_GRADE_BARRIERS[7] && finalGrade <= LETTER_GRADE_BARRIERS[6])
{
    letterGrade = "B";
}
else if (finalGrade >= LETTER_GRADE_BARRIERS[9] && finalGrade <= LETTER_GRADE_BARRIERS[8])
{
    letterGrade = "B-";
}
else if (finalGrade >= LETTER_GRADE_BARRIERS[11] && finalGrade <= LETTER_GRADE_BARRIERS[10])
{
    letterGrade = "C+";
}
else if (finalGrade >= LETTER_GRADE_BARRIERS[13] && finalGrade <= LETTER_GRADE_BARRIERS[12])
{
    letterGrade = "C";
}
else if (finalGrade >= LETTER_GRADE_BARRIERS[15] && finalGrade <= LETTER_GRADE_BARRIERS[14])
{
    letterGrade = "C-";
}
else if (finalGrade >= LETTER_GRADE_BARRIERS[17] && finalGrade <= LETTER_GRADE_BARRIERS[16])
{
    letterGrade = "D+";
}
else if (finalGrade >= LETTER_GRADE_BARRIERS[19] && finalGrade <= LETTER_GRADE_BARRIERS[18])
{
    letterGrade = "D";
}
else if (finalGrade >= LETTER_GRADE_BARRIERS[21] && finalGrade <= LETTER_GRADE_BARRIERS[20])
{
    letterGrade = "D-";
}
else if (finalGrade <= LETTER_GRADE_BARRIERS[22])
{
    letterGrade = "Fail";
}

return letterGrade;
}

Thank!

Answer 1

Yes, any number other than -1.0 or 1 is probably a magic number.

If you are not a real guru, you are probably allowed to use two free forces as well :-)

As an aside, you could probably reorganize this code to be more understandable, for example:

string CalcGrade (int s1, int s2, int s3, double median) {
    // Grade lookup arrays. If grade is >= limit[n], string is grades[n].
    // Anything below D- is a fail.
    static const int Limits[] = {400, 380, 360, 340,320, 300, 280,260, 240, 220,200,180 }; 
    static const int Grades[] = {"A+","A","A-","B+","B","B-","C+","C","C-","D+","D","D-"};

    double finalGrade = s1 + s2 + s3 + median;

    // Check each element of the array and, if the final grade is greater
    //   than or equal to, return the grade string.
    for (int i = 0; i < sizeof(Limits) / sizeof(*Limits); i++)
        if (finalGrade >= Limits[i])
            return Grades[i];

    // Otherwise, failed.
    return "Fail";
}

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, -, 380,5 - :-) "" , 400 ( "A+").

Answer 2

, , . ? - (static const int One = 1; .)

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Answer 3

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Answer 4

, ?

string CalcGrade (int s1, int s2, int s3, double median) {
    int grade = median + s1 + s2 + s3;
    grade = (grade>400)?400:((grade<180)?179:grade);
    return
        "Fail\0D-\0\0\0D\0\0\0\0D+\0\0\0C-\0\0\0C\0\0\0\0"C+\0\0\0"
        "B-\0\0\0B\0\0\0\0B+\0\0\0A-\0\0\0A\0\0\0\0A+"[((grade-160)/20)*5];
}

Answer 5

LETTER_GRADE_BARRIERS , , . int a char * (), .

Answer 6

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Answer 7

, , std::lower_bound, , , , . letter_grade[]= { "A", ... };

Answer 8

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string CalcGrade(int s1, int s2, int s3, double median) {
  const int MAXIMUM_GRADE = 400;
  const int MINIMUM_GRADE = 180;
  const int GRADE_STEP = 20;
  const char* GRADES[] = { "A", "A-", "B+", "B", "B-", "C+", "C", "C-", "D+", "D", "D-" };

  double finalGrade = s1 + s2 + s3 + median;

  if (finalGrade >= MAXIMUM_GRADE) {
    return "A+";
  } else if (finalGrade <= MINIMUM_GRADE) {
    return "Fail";
  } else {
    return GRADES[(size_t)((MAXIMUM_GRADE - finalGrade) / GRADE_STEP)];
  }
}

Answer 9

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paxdiablo - , /.

, :

// original
else if (finalGrade >= LETTER_GRADE_BARRIERS[13] && finalGrade <= LETTER_GRADE_BARRIERS[12]) 
{ 
    letterGrade = "C"; 
} 

// compared to
else if (finalGrade >= MIN_C_GRADE && finalGrade < MIN_C_PLUS_GRADE)
{
    letterGrade = "C";
}

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Answer 10

, LETTER_GRADE_BARRIERS, , , , , .

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