READING
CHAPTER 10
SECTION 1
"Array Basics"

- *array*
  - feature supported by programming languages (PL) to manipulate a collection of values
  - Java: indexed collection of data values of the same type
- declare an array

  <type>[] <identifier>;
  <type> <identifier>[];

- array
  - reference data type
  - amount of memory allocated to store an array varies with the number and type of values in it
  - use reserved word new for array memory allocation
  - but array is not considered an object
- create an array of a given size

  <identifier> = new <type>[<size>];

- can combine declaration and allocation

  <type>[] <identifier> = new <type>[<size>];

- use single identifier to refer to whole collection
- *indexed expression* used to refer to individual values
- *array element* individual value in an array
- zero-based indexing
- biggest index is size-1
- refer to the nth element of an array
  - n can be an expression

  <identifier>[<n>];

- public constant length is the size of any array
  - necessary for iterating through an array using a for loop if the array size is not known in advance

  <identifier>.length

- initialize an array at the time of declaration
  - size of the array
    - do not specify
    - determined by the number of values in the list

      <type>[] <identifier> = {<value 0>, <value 1>, ... , <value n>};

- *fixed-size array declaration*
  - not always most efficient space usage
    - if end up needing more, must change and recompile the program
    - if end up using less, then wasting space
- *variable-size array declaration*
  - can allocate arrays of various size by using a variable (initialized with user input)
    - can also use an expression

Quick Check:
1. c and d are invalid
2. int sum = 0;
   for (int i = 0; i < 25; i++) {
       if (number[i] > 0) {
          sum += number[i];
       }
   }
3. The first method prints out all the evenly indexed elements of the array, while what the second fragment prints depends on the values stored in the array.