Producing Robust Programs

Producing Robust Programs

1. defensive design

   • protection against unexpected user inputs
     • eg. entering a letter when a number was expected
   • maintainability
     • comments, indentation, formatting
   • minimising / removing bugs
     • testing
       • iterative testing: testing that is ongoing throughout development
         • final testing: testing the program as a whole at the end of development
       • valid data
         • invalid data
   • validation
     • first name
       • last name
         • just letters, max charcters 32 min 3
         • DOB
           • DD/MM/YY
           • numbers
             • day) max 31
             • year) max 2022
             • months) max 12
     • email
       • @ symbol
         • no spaces
     • types of check
       • type check: check its the correct data
         • length check: check its the right length
           • range check: check a number falls between two limits
             • format check: check its a certain pattern
               • presence check: check it hasn't been left empty
   • Authentication
     • usernames and passwords allow certain users and limit users access rights