Array Help

[mckizzlealmond]

These arrays are kicking my butt. Can someone help me with what i have so far?

int getGrades(float grades[], int num)
{
   for(int i = 0; i <= num; i++)
   {
      cout << "Grade " << i + 1 << ": ";
      cin >> grades[num];
   }
}

float averageGrades(float grades[], int num)
{
   float sum;
   float avg;
   for(int i = 0; i <= num; i++)
   {
      grades[i] +=sum;
   }
   sum / 10 == avg;
   return avg;
}

int main()
{
   // declare array
   float grades[9];
   //fill them
   getGrades (grades, 9/*numGrades*/);
   float avg = averageGrades(grades, 9/*numGrades*/);
   //display results
   cout << "Average Grade: " << avg
        << "%" << endl;

   return 0;
}

When I run the program, it runs through nicely, until i get to the average.It always comes out as 0%.

Can someone tell me what I'm doing wrong? Thank you for all of the help!

[Zhuge]

Use [code][/code] tags around your code to format it nicely.

On the line after your for loop, you have sum / 10 == avg;. This is incorrect for two reasons: one, that is a comparison, not assignment, and thus doesn't do anything (I presume you meant to do avg = sum / 10;, two, the sum should be divided by the num of elements in the array, not by 10.

Otherwise, it seems you have the idea correct.

[mckizzlealmond]

Oh my goodness, that is EXACTLY what I meant. I kept getting an error when I just did = avg. Stupid mistake. I took you advice, and it still comes out as 0%. Any ideas?

[Zhuge]

What exactly did you change that line to?

Edit: And you seem to have flipped the operands to += inside your loop as well; you probably want sum += grades[i], and you also need to initialize sum to 0 before trying to use it.

[mckizzlealmond]

I changed it to this:
avg = sum / num;

[Zhuge]

Please check my edit in my previous post.

[mckizzlealmond]

Thank you! it is now working. I need to stop flipping the operands. Thanks you again for all the help, this helped me understand arrays that much more.