2.3 Producing Robust Programs

2.3 Producing Robust Programs

1. Data Validation Techniques

   • Check Digit - The last one or two digits are used to check if the rest of the code is correct.
   • Format Check - Checks the data is in the right format.
   • Length Check - Check weather the code is too short/long enough.
   • Lookup Table - Looks up the acceptable values in the table.
   • Presence Check - Checks that the data has been entered into a field.
   • Range Check - Checks if the value falls in the specific range.
   • Spell Check - Looks up word in the dictionary.

2. Types Of Errors

   • Syntax Error - An error in the rule of language/grammar.
   • Logic Error - The program is written do something other that what its intended.
   • Run Time Error - An error you can only spot when a program is running.

3. Test Data

   • Valid - Data that is incorrect.
   • In Range - Maximum data that data could be entered too.
   • Out Of Range - Values higher or lower than the expected range.
   • Null Value - When all the data is left blank to test what happens.
   • Invalid - Incorrect values such as 'Malcolm' for an age range.