[prog] C++

[wolf]

I did finally get the php figured out and handed in the room chart, 
even had a nice button
to click on to print the page : ) However, the lady who enters the room 
data informed
my boss that she had decided she'd rather just use excel then enter the 
info into a database and then print it. Oh well.

As usual, I've been pecking away at the C++ question but not doing too 
well, could anyone
give me a bit of an additional shove? I think I may have picked a 
question way passed
my abilities, altho I think it would be nice to have it save my cd 
library : ) My biggest
accomplishment prior to trying this were functions, so I think I kinda 
jumped a little overboard
with classes : ) I would still like to know how this all would work tho 
: )

Thank you : )


On Mar 3, 2004, at 10:42 PM, Jacinta Richardson wrote:

>
> How'd the PHP stuff go?
>
>> write a program to track a music cd library, allow the user to enter
>> cds. Each item should include the artist, album title, year and genre.
>> All records should be displayed in order by artist. Design this using 
>> a
>> class and represent each cd as an object of that class ( This is the
>> part that is really confusing me). Store the data in a text file so it
>> can be retrieved and viewed.
>>
>> Since I use OSX I was sort of following itunes as an example, I have 
>> my
>> cds listed in a database in mysql, but I don't know if you can connect
>> to that with C++?
>
> You can connect to databases through C++ but I don't think it's talking
> about anything that serious.  I think this is probably what you need 
> to be
> doing:
>
> a) design a CD class:
>
> Class CD:
> 	object private variables:
> 		artist, album title, year, genre
>
> 	methods:
> 		yet to be determined.
>
> b) write code to allow users to enter cds (perhaps using insertion 
> sort)
>
> c) write code to write cd list to a file (maybe best to sort first)
> d) write code to extract cd list from a file.
>
> e) write code to allow the user to view the cds etc.
>
>
> A possible program for this might look like this:
>
> 	Ask user if they want to
> 		a) add a new cd,
> 		b) read in cds from a file
> 		c) list all cds
> 		d) end session
> 		
> 	If a) then
> 		ask for artist name
> 		ask for album title
> 		ask for year
> 		ask for genre
>
> 		create new C++ object with these values
> 		add new object to list of objects.  [1]
>
> 		return to top.
>
> 	If b) then
> 		ask for name of file
>
> 		read in first cd		    [2]
> 		create new C++ object with these values [3]
> 		add new object to list of objects
>
> 		read in next cd and repeat
>
> 		return to top
>
> 	If c) then
> 		walk over list of (sorted) cds and print
> 		out each one
>
> 		return to top
>
> 	If d) then
> 		ask for a file name
> 		write out list of (sorted) cds to file
> 		quit
>
> 	Else
> 		invalid response
> 		return to top.
>
> [1] - I highly recommend using insertion sort to add your elements in.
> What this means is that you always add elements in such a way as to 
> keep
> your list sorted.  For example adding 4 into the following list:
> 	2, 20, 40, 300
> gives us
> 	2, 4, 20, 40, 300
> If you always add elements into this list using insertion sort then you
> will never have to actually sort the list.  There are 3 cases in
> insertion sort and it's best (at the start) to treat them separately.
> The cases are:
> 	1.  Inserting right at the front of the list
> 	2.  Inserting somewhere in the middle of the list
> 	3.  Inserting right at the end of the list
>
> [2] - You'll have to think hard about how you want to represent 
> individual
> cds in your file.  You could do one cd per line with distinct 
> separators,
> such as:
>
> author%%%title%%%year%%genre
>
> or you could write them out in little blocks:
> a:author
> t:title
> y:year
> g:genre
>
> a:author
> t:title
> y:
> g:genre
>
> but you'll need to document your assumptions about the integrity of
> the file.
>
> [3] One of the nice things about object oriented programming is that 
> you
> can hide the representation of things inside the objects.  For example 
> it
> would  make sense to create a "write_to_file(FILE file)" method for 
> the CD
> Class.  This would be called on each CD object and that object would 
> write
> itself to the file.
>
> Likewise a "read_from_file(FILE file)" method would allow CD objects to
> read themselves from the file.  This is really handy because you might
> want to use this CD class (and its stored CDs) somewhere else in other
> code.
>
> In fact, it might even be a good idea to have the object ask the user 
> for
> new cd details (in part a).  This means that if you ever decide to 
> store
> more information about a cd (such as a play list or a filename 
> pointing to
> your mp3 collection) you only need to change the class, not the rest of
> the code.
>
> Of course you're going to want to have the CD print itself out too.  So
> this gives us the following class model:
>
> Class CD:
>         object private variables:
>                 artist, album title, year, genre
>
>         methods:
> 		new		// you always need a constructor
> 		read_from_user()	  // ask user for cd details
> 		read_from_file(FILE file) // read details for 1 cd from file
> 		print_to_file(FILE file)
> 		display_self()
>
> and (for example) part a and b become:
>
>         If a) then
> 		object = CD.new();
> 		if(! object.read_from_user()) {
> 			user didn't give us the right kind of data
> 			return to top.
> 		}
> 		add object to list.
>                 return to top.
>
>         If b) then
>                 ask for name of file
>
> 		while ( 1 ) {
> 			object = CD.new();
> 			if(! object.read_from_file(filename)) {
> 				invalid file or no more entries
> 				break;
> 			}
> 			add object to list
> 		}
> 		return to top.	
>
>
> I hope this helps.
>
> 	Jacinta
>
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