User Input Validation

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User Input Validation

burr 16 Apr 2008 06:14

When you guys are making a game with user input (i.e., using the Input or Prompt commands), how important is user input validation? Do you think it is worth the extra memory needed to implement it? The reason I'm asking is because I'm (slowly) putting together a validation tutorial to cover the main variable types that are inputted in games: numbers, strings, and lists.

I'm at the stage now where I'm trying to think of all of the different things that people should consider checking for when using those different variables, and I was wondering if you guys had any suggestions or ideas? These are the validation "rules" that I have come up with so far:

• Numbers
  • Number is not a complex number
  • Number is within the appropriate range
  • Number is an integer (no fraction part)
  • Number is positive (or zero)
• Strings
  • String only contains certain characters
  • String length is within the appropriate range
• Lists
  • List length is within the appropriate range
  • Each list element passes the number validation

Re: User Input Validation

Socks 16 Apr 2008 16:39

My opinion is that if the user inputs bad data, then any error they get is their fault. I do try to surround the program in a Try…Else…EndTry block for protection against bad data.

I don't get input that way very often any more (I generally use a Dialog) and check it before converting it.

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/Socks

Re: User Input Validation

DarkerLine 16 Apr 2008 16:55

I tend to stick with custom input routines that don't allow you to enter anything invalid in the first place.

Re: User Input Validation

burr 16 Apr 2008 17:02

Yeah, I forgot about making your own custom input routine; that saves me from having to write the validation tutorial.

Re: User Input Validation

GoVegan 16 Apr 2008 21:04

No way, it is still worth the effort. Not all of us like using custom methods (some of us are lazy).

Re: User Input Validation

DarkerLine 16 Apr 2008 21:55

It's not even a laziness issue. It's just that if the entire program is on the graph screen, it would be ridiculous to go to the home screen for input. But if everything else is there, it's perfectly natural.

I would argue that the amount of validation depends on the size of the program and on the kind of mistake. A short math routine probably wouldn't need validation, for example.

Also, there is an alternative approach to validation that can be useful sometimes: find alternate ways of making input acceptable. For example, if the number to be entered is a probability, and the user enters 50, it's likely that they meant 50 percent (so if 1<P and P≤100, divide P by 100). This specific case is actually used by some TI-Basic commands.

Another example: say the input is a list. It could be entered in various ways: with commas and {} brackets, with commas and no brackets, as a list name (L₁ through L₆), or as a name starting with ∟, or as a name without the ∟. Instead of requiring one of these, the program might very well be programmed to handle all of them.

Last edited on 16 Apr 2008 21:56 by DarkerLine Show more

Re: User Input Validation

burr 16 Apr 2008 23:46

Those considerations are primarily why I decided to scrap the validation tutorial idea, although you sound like you could write a pretty good validation tutorial :D

Re: User Input Validation

burr 23 Apr 2008 18:32

I decided to go ahead and write the validation tutorial a few days ago, and I finished putting it together this morning. If anybody has any feedback or suggestions, that would be much appreciated.