[KLUG Programming] sorting, uniq'ing, and grepping

[Tony Gettig]

Quoting Erik Gillespie <rattles@yakko.cs.wmich.edu>:

> > Not quite that simple. He still has to write the comparison code, which
> > is in essense a qsort callback.
> 
> True, the callback can be tricky but in Tony's case he said he's using 
> fixed-width ASCII files with the first 7 characters being the important 
> piece for identifying unique users.  Toss strncmp() in a wrapper function 
> to avoid getting a warning from your compiler and you're good to go:
> 
> int mycompare(const void* a, const void* b) {
>    strncmp((char*)a, (char*)b, 7);
> }

Thanks, Erik! I appreciate this! One of the things I hope to learn through 
this experience is how to think like a programmer and write zippy little 
functions like this. 

> 
> > 0(n log n) performance is what you'll get if you're good. I was not
> > too worried about doing better, and it is possible to do a LOT worse! :)
> 
> It is possible to do worse but if he sorts before searching for uniques 
> and stays away from insertion sort :P he should be fine.
> 

Thank you for the heads up!



-- 
Tony Gettig
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