CODEWITHSUNDEEP
c++arrayscodeblocksaverage
Aaron McAnally
Aaron McAnally

Reputation: 61

Unexpected array behavior in basic averaging program

It seems like I always come here to ask silly questions, but here it goes. As of right now I am in my first compsci course and we are learning c++. I've had an extremely basic introduction to c before, so I had thought I'd go above and beyond my current assignment. Now I was doing this just to showboat, I felt like if I didn't practice my previous concepts they would eventually fade. Anyways, on to the problem! I was supposed to write some code that allowed the user to input their initials, and a series of exams. Now this was supposed to accomplish three things: average the exams, print out the entered exams, and print out their initials. Well, what was a simple assignment, got turned into a huge mess by yours truly.

#include <iostream>
#include <string>
#include <iomanip>

using namespace std;

int main()
{
  string uInitials;
  float avgExam = 0, tExam = 0;
  int aExams[10] = {'0'};
  int i, nExam = 0, cExam;


  cout << "Enter your three initials!";
  cin >> uInitials;


  do
      {

        cout << "Enter your exam(s) to be averaged. Enter 0 when          complete!\n";
        cin >> cExam;
        aExams[nExam] = cExam;  //I used this before nExam was incremented, in order to get nExam while it was '0' That way the first exam score would be properly saved in the first space
        nExam++;
        tExam += cExam;     //This is just to add all the exams up to later calculate the average
    }
  while(cExam != 0);

avgExam = tExam/(nExam - 1); //subtracted '1' from nExams to remove the  sentinel value from calculations.

cout << "The average for initials: " << uInitials << " is: " << avgExam <<   endl;
cout << "This average was obtained using the following scores that were entered: \n";

for(i = 0; i < (nExam+1); i++)
{
    cout << aExams[i] << endl; //Used a for loop to prevent redundancy
}

return 0;
}

The previous is my code, and the problem is that I'm getting output errors where it adds two '0's when I print out the list of entered exams. Also I feel like I made the whole do{}while() loop one huge clunky mess, so I'd like to refine that as well. If anyone could assist this poor, ignorant, beginner I would greatly appreciate it. Thank you for your time!

Upvotes: 1

Views: 59

Answers (2)

fdsfsfs
fdsfsfs

Reputation: 26

Some advice that i can give is for example in the 5th line there is no need to put the 0 between ' ' and not even need to use the assign = operator. You can initialize the array like this: int aExams[10]{0}; Which will initialize all elements to 0,but can't be used for other value. For example you won't have all the elements with value 1 if you write int aExams[10]{1}; If your intention to initialize all elements in an array is with value other than 0 you can use fill_n(); function.

fill_n(aExams, 10, 1); The first argument is the name of the array, the second is up-to which element you want to be initialized with the third argument, and the third is the value you want all elements to have.

Do not leave uninitialized variables like in line 6 with cExam and i variables. Initialize it like cExam=0; (copy-assign initialization) or cExam(0); (direct initialization). The latter calls the constructor for int built-in type.

A negative i see in your do-while loop is that you do not make sure that the user will enter under 10 exams,bad things will happen if the user tries to input 15 exams in an array that can hold only 10.

Just change the while to something more like this: while( cExam != 0 && (nExam<10) );

You can also write the first two lines of the do-while loop outside the loop. It is needed only once to tell the user that to stop the loop he/she needs to enter 0. There is no need to tell them this on every iteration plus that you will have a good performance benefit if you put those two lines outside the loop.

Look here how i would write the code and ask if you have any questions.

http://pastebin.com/3BFzrk5C

Upvotes: 1

giraffesyo
giraffesyo

Reputation: 5342

The problem where it prints out two 0's at the end of your code is a result of the way you wrote your for loop.

Instead of:

for(i = 0; i < (nExam+1); i++)
{
    cout << aExams[i] << endl; //Used a for loop to prevent redundancy
}

Use:

for (i = 1; i < (nExam); i++)
{
    cout << aExams[i - 1] << endl; //Used a for loop to prevent redundancy
}

Upvotes: 1

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