[OCLUG-devel] Lexicographically Sorted

[Christopher Smith]

Chris Berry wrote:

> That's interesting, and kind of scary, seems like every time I learn 
> something new about computers it just reveals a whole new layer of 
> ignorance on my part. Unfortuneately, the man pages you pointed to 
> don't define lexicographic ordering. I'm not looking for a strcmp 
> replacement, I'm doing an excercise as part of my C programming 
> training. I don't want someone to do the work for me, I just need to 
> know what lexicographical order is so I can figure out how to write 
> the algorithm.
>
Apologies. I thought the man pages would make it clear. Alphabetical 
ordering is a subset of lexical ordering. The difference is that lexical 
ordering allows for sorting of non-alphabetical characters. All this 
stuff is dealt with in detail in the locale support in POSIX (see the 
link I provided). strcoll is not a strcmp replacement. They are similar 
functions. strcmp compares strings based on ASCIIbetical order, strcoll 
compares strings based on lexical ordering for the current POSIX locale.

POSIX is a standard seperate from the C language, so strcoll is 
technically not part of C and perhaps using POSIX functions is 
inappropriate for your situation, in which case you need to match 
strcoll's functionality. Basically, the main thing you need is a lexical 
alphabet to define what comes before what and what characters are 
equivalent. If you can't use POSIX, you are going to need some other 
source for determining that. Since you didn't mention having one, I 
figured using POSIX was the way the instructor wanted you to go.

--Chris