3.2.5 - Writing maintainable programs

3.2.5 - Writing maintainable programs

1. 3.2.5a - Programming definitions

   • Definitions that should be understood:
     • Variable: A memory location used to store data. Uses a variable name which allows data to be stored, retrieved and manipulated without knowing what the data will be
     • Constant: A data item with a fixed value.
     • Identifier: The name of the object chosen by the programmer. Can relate to a variable, function, procedure etc.
     • Reserved Word: Any vocabulary of a programming language that can only have the meaning assigned to it within the language. It cannot be assinged as an identifier

2. 3.2.5b - Readability

   • A program should be written in a way that makes it easy for the user to understand it when the program is read.

3. 3.2.5c,d,e - More terminology

   • Most procedural languages allow variables and constants to be used:
     • Variable: Name that refers to a particular memory location that stores data. The value of data held is unknown and can change when the program is run.
     • Constant: A name used to refer to a fixed value. The value is set at the start and cannot change whilst the program is running.
     • The name of a variable or constant is also called its identifier.
   • Scope refers to the availability of a variable:
     • Local: One that is declared within a module, subroutine, procedure or function and is only available there.
     • Global: One that is declared at the beginning of the code and can be used at any point.

4. 3.2.5f - Initializing variables

   • Some languages will initialize variables when they are declared.

5. 3.2.5g - Modularisation

   • Code can become far easier to read if it is written in modules.
     • Complex operations can be broken into subroutines that are defined seperately

6. 3.2.5h - Comments

   • Commenting code allows programmers to gain an understand when reading code
     • There are instances where comments should be included

7. 3.2.5i - Indentation

   • Indentation is a way of making code more readable. Having blocks sticking out makes it easier to separate blocks of code.