3.13 Developing Procedures

1. Exam Points

• Develop procedures and call procedures
• Benefits of procedure abstraction
• Use parameters to generalize functionality
• Extract shared features to generalize functionality
• Note:
  • Decide whether a procedure returns a value, if it does, use the RETURN statement in the procedure.
    

2. Knowledge Points

(1) Procedural Abstraction (The Process of Creating Procedures)

• Procedural abstraction: provides a name for a process and allows a procedure to be used only knowing what it does, not how it does it.
• Example: Create a procedure(reuse) to compute the sum of all the elements in a given list.
  
  
• Procedural abstraction allows a solution to a large problem to be based on the solutions of smaller subproblems, therefore, creating procedures to solve each subproblem.
• Example: create procedures for different tasks.
  
  
• A procedural abstraction may extract shared features to generalize functionality instead of duplicating code.
• The subdivision of a computer program into separate subprograms is called modularity (模块化/性).
• This allows for program code reuse, which helps manage complexity.
• Using procedural abstraction helps improve code readability.
• Programmers break down problems into smaller and more manageable pieces.
• Procedures allow programmers to draw upon existing code that has already been tested, allowing them to write programs more quickly and with more confidence and less errors.
• Summary:
  • modularize a big problem into more managable sub problems, helps manage complexity.
  • improves code reusability, reducing duplicate code.
  • code well structured, more readable and easier to maintain.
• Using parameters allows procedures to be generalized, enabling the procedures to be reused with a range of input values or arguments.

(2) Develop and Call Procedures

• Develop and call a procedure:
  
• Example: Develop a procedure
  
• Example: Call a procedure
  
  • sum1 ← sum(aList)
  • sum2 ← sum(bList)

3. Exercises

• Practice
• Solution