Hi Mary:
I made all the changes in about three minutes so there wasn't that much really wrong. I did change the indentation to match my own style but that's just different; yours is certainly not wrong. I had to make up a fake load_array function since your code didn't have one. I assume the real thing loads from a file, pipe, or database.
1) I changed the include statements to bring in more appropriate header files; specifically those which have the prototypes for qsort & strcmp.
2) Note that I changed your declaration of your struct to a typedef AND now we have 'desc_struct' instead of 'struct DESC_STRUCT'; it's much easier to type but more importantly I separated the declaration of your array from the typedef of the struct.
Typically, data structures used by several files should be put in a header file (e.g. local.h) and #include'ed.
3) I changed your array size '1000' to a define. This means that any change in the future just requires that you change that one define.
4) Your compare_desc_structs function has very loose typing. Note that now, the formal parameters conform to the prototype that qsort expects but the pointers are explicitly cast as pointers to the needed type. This is considered a much cleaner coding style. Note also that I went through a few hoops to make sure that the function returns a completely valid int rather than a long. This is actually a bit of overkill but for teaching purposes, it's the really tight way to do it.
5) You main was declared int but you didn't return a result. Because the OS evaluates this return value, you should always make certain your main returns with a value or that you call exit() with a value.
6) Minor point but notice the (void) before the printf()'s and sprintf()'s. This is a way of saying yes, I know you return a value but I am explicitly ignoring it.
7) Note that most of the functions are now declared static (i.e. file scope). If a function does not need to be visible outside the file then use the static declaration.
The last point is the one that first caught my eye. Why the limit of 1000? I know - you'll never have that many. Famous last words. The best way to do this is with dynamic arrays. They are quite easy to implement and accomplish two things: 1) No limits 2) No wasted space because you declare huge static arrays that are almost always very sparsely populated. Once you create a set of dynamic array routines, you find that they will replace most of your static arrays and most linked lists as well.
P.S. Learn to use lint. It would have caught most of this stuff.
Hopefully, I've been a good boy and haven't clobbered you.
Regards, Clay
If it ain't broke, I can fix that.
