Producing Robust Programs (2.3)

• to clean up input data, removing any unwanted data such as extra spaces, or removing special characters/symbols. This also helps prevent SQL injection.

• validating the data entered so that it fits a range of values, or is of a specific type. Entered data must fit criteria to prevent logical errors and unexpected outcomes

• only allowing authorised users to access data through use of usernames and passwords etc.

• this allows other programmers to also understand the code, especially when dealing with large programs

• Comments : annotating the code to make it easier to understand and read • Indentation : spacing the code appropriately, so it is easily to follow different sections of the program and what they do • Meaningful identifier names : using appropriate names for identifiers (variables, constants etc.) linked to the purpose so it does not cause confusion • Use of sub-programs : allows programmer to structure code so parts can be developed and changed independently without affecting the rest of the program

• Testing allows the programmer to test the function of programs to make sure they work as expected

• carried out while the program is being developed (ongoing) so different sections of code are tested out by the programmer

• carried out when all the sections of the program and code have been completed and developed. The program is tested as a whole to make sure it functions as expected.

• selecting valid/expected values to see if the program accepts these without causing errors e.g. if the valid numbers are 1-10 then choose a number within this range

• selecting data which the program should not accept such as entering “six” as string instead of 6 as integer so it should be rejected

• selecting values which lie on the boundary of the accepted range of values e.g. if 1-10 are valid values then entering 0,1,10,11 are boundary data