Thread: Debugging homework assignment/ questions surrounding partially filled arrays

Most likely you may need to clear the buffer after reading in the double. This is a pretty common issue when using scanners.

Originally Posted by Parranoia

Most likely you may need to clear the buffer after reading in the double. This is a pretty common issue when using scanners.

I thought it was that but it turned out I had to put something in for the hasNext() clause. I added a trash variable to hold my input for when it didnt fit the if clause and I got it to work.

 
if  (index < arrayLength)
          { arrayVals[index] = input.nextDouble();
            index++;
          }
 
          else 
          { trashCan = input.nextDouble();
          }

Cross posted here.

Originally Posted by Helplessdrowningpuppy

I thought it was that but it turned out I had to put something in for the hasNext() clause. I added a trash variable to hold my input for when it didnt fit the if clause and I got it to work.

Using a trash variable is not a good way to implement this unless you are required to store or do something with the excess numbers. Using the trash variable slows down your program needlessly (which is not noticeable in this case, but what if there is a very long list of numbers?), and is not a good habit to get into. Instead, you should add a condition in the while loop to check that the array index is less than the length of the array, e.g.,

while (input.hasNext() && index < arrayLength)

This way you can even dispense with the if check in the body of the loop.

Note that I'm assuming you're not interested in reading all the numbers in the file. If you are, then you can either increase the size of the array, or use a variable-size list such as ArrayList or LinkedList.

Originally Posted by jashburn

Using a trash variable is not a good way to implement this unless you are required to store or do something with the excess numbers. Using the trash variable slows down your program needlessly (which is not noticeable in this case, but what if there is a very long list of numbers?), and is not a good habit to get into. Instead, you should add a condition in the while loop to check that the array index is less than the length of the array, e.g.,

while (input.hasNext() && index < arrayLength)

This way you can even dispense with the if check in the body of the loop.

Note that I'm assuming you're not interested in reading all the numbers in the file. If you are, then you can either increase the size of the array, or use a variable-size list such as ArrayList or LinkedList.

We run this program twice with different input files, one of length 6 and one of length 19, but we have to use an array size of 15, to get us used to dealing with partially filled arrays. I used the counter because we need to count the number of items which couldnt fit into the array and output the information, if there were extras, srry if I didn't make it clear, I wrote this in a rush but I had weird specs for the program from my professor.

Originally Posted by Helplessdrowningpuppy

So I'm working on a program that so far

1) reads a set of numbers from an input file, puts them into an array. The array length is a constant number, but the input file (I run the program twice with different input files) either has more or less then the array size. I'm supposed to count the number of elements in the file including the ones which didnt fit in the array.

This is my code so far.

 
    int numOfItems;             // num of items in the array
    final int arrayLength = 15; // setting the array length

Your array length is set to 15, but you have 19 values?

Originally Posted by Leklur

Your array length is set to 15, but you have 19 values?

Yeah its part of my assignment, we were supposed to read the values from the input file that would fit into the array, and keep a tally of all the values processed so we could output to the console how many values were extraneous if any. So in this case I would output that I had 4 extraneous values.