Procedural Abstraction

• Functions should be written as "black boxes"

  • The function should do some describable unit of work

  • The user of the function should only be concerned with what the function does, not how

  • All control of the function should be affected through the parameters

    • The function should use only variables which it declares locally

  • If the function has a single output, it should be provided to the calling program via a return statement

• Thinking about functions as "black boxes" is called "procedural abstraction"

• Complicated algorithms or procedures can be made simpler by breaking them up into smaller units of work (divide and conquer).