HW1_SD

The Implementation of the Assignment

The assignment was completed in 3 weeks.

The implementation ideas came to me successively.

Week 1

• In the first week, I conceived the necessary structures and the logic of the entire program.
• I used while(1) and fgets to obtain data from the file.
• I also implemented the 'save' and 'quit' commands, as they were the most basic.

Week 2

• In the second week, I performed the 'da', 'd', 'b', 'gl', 'gc' operations.
• This week presented the most obstacles.
• The delete operations generated many errors because it was necessary to traverse the large list (LIST is a doubly linked list of lists).
• Approximately 2-3 days of this week were needed for debugging.
• I used valgrind and GDB. valgrind reported the most errors.
• The move operations (gl, gc) were straightforward.
• The main idea of the program conceived so far is:

      NULL
       ^
       |
 NULL<-a-><-a-><-a-><-a-><-a->NULL
       ^
       |
       v
 NULL<-b-><-b-><-b-><-b-><-b->NULL
       ^
       |
       v
 NULL<-c-><-c-><-c-><-c-><-c->NULL
       |
       v
      NULL

I represented the text:

aaaaa
bbbbb
ccccc

This is what I meant when I said "large list" (each line represents a doubly linked list).

The meanings of the following fields:

• next: move one character forward.
• prev: move one character backward.
• nextlist: move to the beginning of the next line.
• Example: If I'm at the beginning of line 2, I'll reach c after the b->nextlist operation.
• prevlist: move to the beginning of the previous line.
• Obviously, the first line is LIST->HEAD, and the last line is LIST->TAIL; LIST->HEAD->prevlist -> NULL, and LIST->TAIL->nextlist -> NULL.
• LIST2 is the list of lists for commands.
• As I said, many errors in this part of the program.

Week 3

• In the third week, I finalized the assignment.
• The experience gained in the second week saved me from other errors.
• In this week, I performed the remaining commands: undo, redo, re, ra, dl, etc.
• For undo/redo, I used a stack, as it was a requirement.
• The undo operation for inserting text was straightforward, I used an auxiliary list.
• The redo operation for inserting text was trivial, I called the add function that takes the large list and a list (line of text).
• Performing the ra operation took an entire day. I put the arguments in 2 lists and traversed the large list.
• Conceiving the re operation took 2 hours.
• I spent 5 days to devise the undo operations (re, ra, d, etc.).
• The undo operation for re was straightforward, I used the command with the arguments reversed.
• I handled all cases for each command.
• For all redo operations, I popped from the stack and used the goto statement.
• I also used these char* variables (s1, s2, s6, etc.) for memory deallocation (valgrind).

In conclusion, this was not a trivial assignment.