Topics: Structures, Arrays, Searching and Sorting

Assume there is a small mobile computer device including a
hard disk and a slot for a memory card. The device shall be
used to backup photos e.g. during holiday. Every time a
memory card is connected all photos of the card are copied
into a new folder automatically. And your task is to
develop some basic controlling software to show, add,
remove, search and sort the directories of photos.



Step by Step Implementation


1.Define two symbolic constants, one to hold the total
volume of the disk (e.g. VOLUME) and another one to hold
the number of entries the files system of the device can
handle (MAXFOLD).

2.Define a new structure data type named DATE to store a
date consisting of year, month and day as unsigned values.

3.Define an other structure data type FOLDER to store the
information of one folder of photos:


◦A title as character array of appropriate length
◦The location (event) the photos are taken as character
array of appropriate length
◦The date of the day the photos are copied to the disk
using the just defined data type DATE
◦The number of photos as natural number
◦And the size of the folder in MB as floating point value

4.Define the following global variables and initialise
them:


◦disk as an array with MAXFOLD elements of data type FOLDER
◦folders as natural value to count the number of folders
currently stored at the disk (valid elements in the array)

TEST: Now you should be able to compile the code the first
time without any warning or error. In the menu only "p" to
print and "q" to quit will work!.



5.Now complete the functions given by their prototype:
float freeSpace ();The function has to calculate the sum of
the size component of all elements currently stored in the
disk array. The function shall return the free space of the
disk by the difference between the available total volume
and the calculated sum.

TEST: To test this function you only need to uncomment
printing the "statusline" at the function actionmenu().
Compare the calculated value with a manual calculation of
the example values given above.

unsigned isBefore (DATE, DATE);The function checks if one
date is before the other. There are 3 different
possibilities which have to be handled. Imagine for example
these 3 different combinations of values:

◦2010-01-01 : 2010-01-02
◦2010-01-01 : 2010-02-01
◦2010-01-01 : 2009-01-01
The function shall just return the result of the comparison.


unsigned isEqual (DATE, DATE);The function checks if one
date is equal to the other, all components have to be
compared. The function shall just return the result of the
comparison.

int findByDate (DATE);As the array is should be kept in
order (sorted by date) implement a binary search for a
folder by its date here. You need only to adapt the binary
search we used in the exercise. Use the 2 comparing
functions above where appropriate. The function shall
return the index of the element which was found or -1.

TEST: Now you can try searching a folder by date via
the "s" in the menu. Activate the corresponding part in the
main function.

int isSpaceLeft (FOLDER);This function compares the free
space of the disk with the size of folder given with the
parameter list. The function shall return 1 if there is
enough space to add the folder, otherwise 0 (just the
result of the comparison).

void SortByDate ();This function shall implement the
InsertionSort using the component date as key. Use the
provided algorithm/souce code of the exercise as template.
If you need a comparison between dates, use the function
isBefore you have written again.

void addFolder (FOLDER);The function has to check if the
disk has additional capacities to add the new folder
(number of folders and space left). If at least one of
these conditions is false print an error message and
return -1. Else there has to be added an other test to
avoid 2 folder elements with the same date (use the
findByDate function here. If there is no folder with the
new date simply attach the new folder at the end of the
array and call the sorting algorithm afterwards to keep the
order in the array.

TEST: Now you can try to add a folder via the "a" in the
menu. Activate the corresponding part in the main function.

void delDir (int);This function removes one element of the
disk array. The input parameter contains the index of the
element to delete. Deletion can simply be done by moving
all elements at the right one to the left (overwriting the
element to delete. The function may get a -1. This has to
be checked first (certainly there is nothing to delete
then!) Don't forget to decrement the counter of elements at
the end.

TEST: Now you can try to remove a folder by date via
the "r" in the menu. Activate the corresponding part in the
main function.

unsigned findAllOfLocation(char[], FOLDER[]);This is an
optional additional task: The function shall find all
elements with the given value for the component location
(first input parameter). The array elements which are found
have to be added to the FOLDER array (second input
parameter). As this parameter is an array we can use the
result later in the main function. There kernel of function
implements a modified linear search on the disk array (it
does not stop if one element is found bat continues search
until the location of all elements is checked). The finally
function shall return the number of elements found in the
disk array.

TEST: Now you can try to add a folder by date via the "l"
in the menu. Activate the corresponding part in the main
function.