3.2 Data Abstraction (list)

1. Exam Points

• Benefits of using lists.
  • Lists often allow their size to be easily updated to hold as many data values as needed. (append, insert, remove etc.)
  • Easier to apply the same computation to every element.
• Index of list elements start from 1, ends at size.
• Indexex of String characters start from 1. (Ex. ”abc”, the index of a is 1)
• Predict the result after some operations on a list.

2. Knowledge Points

(1) list (列表)

• A list is an ordered sequence of elements(元素).
• Format: [value1, value2, value3, ...]
• Example:
  
  • [10, 20, 30, 40, 50, 60]
• An element is an individual value in a list that is assigned a unique index.
• The valid index of a list is of range: 1 to size
• Here value1 is the first element, value2 is the second element, value3 is the third element, and so on.
• An index is a common method for referencing the elements in a list or string using natural numbers (1,2,3,…).
• Example:
  • [10, 20, 30, 40, 50, 60] : index of 10 is 1, index of 60 is 6.
  • Annabelle: index of A is 1, index of b is 5.
• Data abstractions reduce complexity in programs by giving a collection of data a name without referencing the specific details of the representation.
• Data abstractions can be created using lists.

(2) Create a list

• Syntax:
  
• Example:
  
  • Create a list: aList ← [10, 20, 30, 40]
  • Create an empty list: bList ← []
  • Assign a copy of aList to bList: bList ← aList

3. Exercises

• Practice
• Solution