Desk Checking (1 Viewer)

[adamj]

Whilst it is something that seems so simple, I am a little confused at how to construct a desk check table. So I am wandering if anyone can clarify it, I refer to the Sam Davis Textbook which ought to be commended for explaining it in the most practical way on page 211.

 

[kamankitty]

desk checking is the process of working through an algorithm or piece of source code by hand. it is used in testing and correcting a program.
test data is used to compare the actual result the program produces to the expected results.
to find where an error occurs, the programmer, or a peer, uses a structured walk through to step through the code and finds where the error has occured.

def: checking the validity of an algorithm by working through the written version of the algorithm using test data

 

[Winston]

Originally posted by adamj
Whilst it is something that seems so simple, I am a little confused at how to construct a desk check table. So I am wandering if anyone can clarify it, I refer to the Sam Davis Textbook which ought to be commended for explaining it in the most practical way on page 211.

All you do for desk check tables is for each column represents a variable

so if the algorithm has variable count

you have a column for count

 

[Winston]

Originally posted by kamankitty
desk checking is the process of working through an algorithm or piece of source code by hand. it is used in testing and correcting a program.
test data is used to compare the actual result the program produces to the expected results.
to find where an error occurs, the programmer, or a peer, uses a structured walk through to step through the code and finds where the error has occured.

def: checking the validity of an algorithm by working through the written version of the algorithm using test data

hmm great but adamj wanted to know how to construct a desk check table not the definition for it.

 

[adamj]

Thanks, but how do you know when to start a new line?

 

[Winston]

Originally posted by adamj
Thanks, but how do you know when to start a new line?

you mean start a new row for the results?

well you start a new row when you that specific piece of data has finished being processed in the algorithm.

 

[Seraph]

my silly willy nilly Excel SDD book says
the columns in a desk checking table should be
Inputs
Expected Result
Actual Result

 

[Winston]

my silly willy nilly Excel SDD book says
the columns in a desk checking table should be
Inputs
Expected Result
Actual Result

That's truthfully not a silly thing... In general unit testing reports that's how it's performed...

Purpose, Data Input, Expected Output, Actual Output.

What Desk Checking in the HSC is, is essentially what we would all call Code Tracing, because basically you have a column for each variable and you're just monitoring that as you go through the code, the data that's expected is correct for each variable.

 

[SamD]

Thanks, but how do you know when to start a new line?

Adamj, don't worry too much about when to start a new line, it's not really the point of a deskcheck. Indeed you could just write any changed values directly under the previous value without even worrying about lining up values into rows. However in practice, not lining up values across the row makes it difficult to complete the deskcheck, and secondly it makes it difficult to analyse or check your deskcheck later (or more critically it makes the HSC marker's job more difficult). Therefore, as a general guide, I'd advise you to start a new row at the start of each iteration. Furthermore, don't transcribe entries into the new row from above, the assumption being that the entry in each column above the current row is the current value of that variable. And every entry in the table is made as a result of some statement executing in the alogrithm.

HTH
Sam

 

[Winston]

lol Sam, did you realise that post was last years?

 

[SamD]

lol Sam, did you realise that post was last years?

I do now! Bugger, waste of time. Thanks Winston, I'm going to bed!!!!

 

[Krishh]

I do now! Bugger, waste of time. Thanks Winston, I'm going to bed!!!!

Not a waste Sam, helped me out 19 years later.

 

[Socialism]

Not a waste Sam, helped me out 19 years later.

Yeah! (That makes me feel young)

 

[liamkk112]

I do now! Bugger, waste of time. Thanks Winston, I'm going to bed!!!!

wait this is litearlly samuel davis wtf