software design and development

• analysis - Given a problem, identify what a program is meant to do.
• design - Use tools such as pseudocode, structure diagrams, flowcharts and wireframes to set out the functionality and interface of the program.
• Implementation - Write the program.
• testing - Check that the program works as expected and has no errors.
• documentation - Collect the documents which are generated at each phase of the software development process.
• evaluation - Review the program to check if it:

  • is fit for purpose
  • makes efficient use of code
  • is robust
  • is readable
• A program is fit for purpose if it meets the requirements specification set out during the analysis phase. the final program should match the purpose and functional requirements.
• Efficient code uses less resources (processor, RAM) and executes more quickly.
• Code can be made more efficient by:

  • Using repeat loops wherever possible
  • Using complex conditions instead of simple conditions
  • Using arrays instead of multiple variables
• A program is robust if it can handle a range of different inputs without crashing.
• A program is made more readable by using the following techniques:

  • ​​internal commentary
  • meaningful variable names
  • indentation
  • white space
• readability

  A) internal commentary

  B) indentation

  C) meaningful variable names

  D) white space

  
• A logic error does not cause the program to crash, but it will produce unexpected results.
• Execution errors (also called run-time errors) will cause the program to crash unexpectedly.
• Syntax errors are errors in code such as mis-spelled keywords or incorrect use of the programming language rules.
• Normal test data will show that the program works as expected.
• Extreme test data is used to test the boundary limits of a program.
• Exceptional test data is used to test that the program can handle unexpected inputs.
• structure diagram

  A) process

  B) loop

  C) predefined function

  D) selection

  E) process

  F) process

  
• flowchart

  A) terminal

  B) represents start and end of a problem

  
• flowchart

  A) initialisation

  B) used to show declaration of variables

  
• flowchart

  A) input/output

  B) shows data input or output

  
• flowchart

  A) Decision

  B) problem may branch or repeat if conditions are not met