Programming Techniques

Programming Techniques

1. Stepwise Refinement

   • Problem broken into sections which become progressively smaller until each section can be written as a single procedure/represents one step in the algorithm
     • Each end node of a top down design tree can be written as an individual function or procedure,
   • Advantages
     • Can program individual sections in different languages most suitable for the function
     • Individual programmers can work on individual modules. which can function independently
       • Then be linked
     • Modules can be tested individually.
       • Simplifides testing. If modules work independently

2. Return Types

   • Functions
     • Functions are individual blocks of code which are run when called.
     • Can have input parameters. Global variables can be passed in and used locally.
   • Procedures
     • Individual blocks of code which perform a specific funciton.
     • Has input parameters
     • When called, a procedure will always return a value.

3. Scope Of Variables

   • Local
     • Declared within a subroutine
     • Can only be used within the subroutine where they were declared.
     • Efficient. Releases memory when containing subroutine has run.
   • Global
     • Declared at start of program
     • May be used directly anywhere in code
     • Can pass into subroutine as a parameter
       • Creates a copy of data in local variable, keeping global value intact.

4. Stacks

   • First In Last Out
   • Dynamic structure
   • Can be used to reverse order of data set.
   • Can be used to evaluate instructions in RPN