Summary Programming Logic and Design Ch 6

Chapter 6
Store data in arrays
 Array
 A series or list of variables in computer memory
 All variables share the same name, and must be the same data type
 Each variable has a different subscript [0] [1] [2]


 How arrays occupy computer memory
 Element: an item in the array
 Initialization list: values assigned to array elements in declarations (num prices [3] = 25,
36, 47)
 Size of the array: the number of elements it will hold
 Subscripts or indexes: position number of an item in an array, subscripts are always a
sequence [0] [1] [2]
 Adding data values is called populating the array


Describe how an array can replace nested decisions
 The array reduces the number of statements needed
 Six count accumulators are redefined as a single array (count [x] where x is between 0 and 5)
 Variable as a subscript to the array
 Array subscript variable must be:
 Numeric with no decimal places
 Initialized to 0
 Incremented by 1 each time the logic passes through the loop (count = count + 1)


Use constants with arrays
 Use constants in several ways
 To hold the size of an array
 As the array values
 As subscripts


 Avoid "magic numbers" (unnamed constants)
 Declare named numeric constant to be used every time the array is accessed
 Make sure any subscript remains less than the constant value
 Constants are created automatically in many languages


 Sometimes the values stored in arrays should be constants
 Example string MONTH [12] = "Jan", "Feb", "Mar", "Apr", "May", ...