2.1.2 Thinking ahead

What is the purpose of thinking ahead?

• To make programs easy and intuitive for users to use.

• selecting data from a larger pool to show only the relevant details to the object. It helps to reduce programming complexity and effort.

• break down your project scope into manageable chunks.

• observe and analyze phenomena, reactions, and feedback and then draw conclusions based on that input.

Define inputs.

• Any data that is required to solve a problem, usually entered into the system by the user.

• Hardware peripherals

• The results that are passed back once the outputs have been processed and the problem solved.

• Open source software

• proprietary software

Define outputs

• The results that are passed back once the inputs have been processed and the problem solved.

• Any data that is required to solve a problem, usually entered into the system by the user.

• Hardware peripherals

• Open source software

• proprietary software

What considerations do programmers need to make regarding inputs and outputs when thinking ahead?

• Method of input/output (device used)

• Data structures used

• Data types used

• Order of data

Identify the inputs that are likely to be used in a book reservation system i.e. at a library.

• Book details: name, author

• ISBN

• Borrower details: name, library card<br />number

• Collection point

• Book cost

Identify the outputs that are likely to be used in a book reservation system i.e. at a library.

• Expected waiting time

• Confirmation

• Availability at other libraries

• Book cost

• Borrower details: name, library card number

What are preconditions?

• Requirements which must be met before a program can be executed.

• Requirements which must be met before a program can be designed.

• Requirements which must be met before a program can be concieved.

• Requirements which must be met before a program can be tested.

Where can preconditions be defined?

• Within the code or within documentation.
• Within the code
• Within documentation

State two advantages of including preconditions within the documentation accompanying a subroutine.

• Reduces the length of the program

• Reduces the complexity of the program

• Reduces the running time of the program

• Reduces the length of the documentation

Define caching.

• The process of storing instructions or values in cache memory after they have been used, as they may be used again.

• Requirements which must be met before a program can be executed.

• Requirements which must be met before a program can be designed.

• Requirements which must be met before a program can be concieved.

• Requirements which must be met before a program can be tested.