Notes on Program 2

Array Declaration

• Array size must be specified at compile time, not run time.
• Right:
  const MAX_ELEMENTS = 50;
  …
  int theArray[MAX_ELEMENTS];
  float values[10];
• Wrong:
  int size;
  …
  cin >> size;
  int theArray[size];

Finding the Largest Value in an Array (or the Mode)

• Choose a current largest value, compare each array element to it. If an element is larger than currentLargest, replace value of currentLargest with new value.
• Right:
  currentLargest = frequency[0];
  for(i = 1; i < size; i++) // can also use a while loop
  if (frequency[i] > currentLargest)
  currentLargest = frequency[i];
• Wrong:
  currentLargest = frequency[0];
  for(i = 0; i < size; i++)
  if (frequency[i+1] > frequency[i])
  currentLargest = frequency[i + 1];
  
  

Finding The Median In An Array

• Use the “%” operator to determine if the number of elements is odd or even.

• For an even number of values, say 8, the array indexes are 0, 1, 2, 3, 4, 5, 6, 7. The median is the average of the two middle numbers – in this case, array[3] and array[4]. In general, find the average of array[size/2 - 1] and array[size/2] (or, array[(size-1)/2] and array[(size-1)/2 + 1] )
• For an odd number of values, choose the middle element: array[size/2] (or, array[(size-1)/2 ] - since it’s integer division, you get the same answer either way).
  
  

Functions

• Use the BubbleSort function as a function.
• Don’t modify the function or add to it – a function should be cohesive.
• Cohesive functions have a single purpose – solve one logical problem
  
  
  

Printing 10 elements per line

for (i = 0; i < size; i++)
if(i % 10 == 0)

cout << endl;

cout << val[i] << endl;