Difference between two files

Question

Hi, I need to find difference between two files.
This is an example:
oldfile.txt:
This is the old file.
I need some help with
this task!.
newfile.txt:
This is the new file.
I need help with this task please!.
Differences:
* old -> new
* need -> need
* "some" was deleted
* please was added
Notice that I don't care spaces, new lines or tabs.
The code should looks like:
enum DifferenceType { Added, Deleted, Replaced };
class DiffText {
  public String Text;
  public DifferenceType Type;
  public String ReplacedText;
  Diff d = new Diff("oldfile.txt","newfile.txt");
  while(!d.end()) {
    DiffText dtext = d.getNext();
   String s = "";
    switch(s.Type) {
      case Added:       System.out.println(s.Text + " ~ added");
      case Deleted:    System.out.println(s.Text + " ~ deleted");
      case Replaced: System.out.println(s.Text + " replaced by " + s.ReplacedText);
  }Thanks for your help in advance.

Answer 1

Suppose you have two arrays filled with integers.
What you want to do is map the integers from one
array to the other.
In your example, your arrays would look like:
this is the old file i need some help with this task
[0 1 2 3 4 5 6 7 8 9 0 10]
this is the new file i need help with this task please
[0 1 2 11 4 5 6 8 9 0 10 12]
Here, I've assumed you've removed all punctuation and
new line characters, and changed to lowercase.
The easiest way is to walk through the arrays greedily.
However, you may be able to research algorithms that
do a better job of matching.