CSC 104 Slog-Week Seven (Feb 25th - Mar 3rd)

CSC 104 Slog-Week Seven (Feb 25^th - Mar 3^rd)
❤Something new learned in the class:

[Computer system]

  ❀Sound can be represented by sampling the amplitude (strength) of the sound wave at regular intervals, and storing the strengths as numbers.

  ❀Images can be represented as a grid of numbers, with each number representing the strength of a particular color in one pixel (picture element) of the image. Since a detailed picture contains a large number of pixels, a great deal of storage is needed. Different image formats make different choices about how many different colours to encode for each pixel.

Computer Designers are so awesome!

[Dr.Racket]

  ❀rot13: produces character 13 places (cyclic) ahead

(define (rot13 c)

  (cond

    [(char<=? #\A c #\M) (integer->char (+ 13 (char->integer c)))]

 [(char<=? #\a c #\m) (integer->char (+ 13 (char->integer c)))]

 [(char<=? #\N c #\Z) (integer->char (- (char->integer c) 13))]

 [(char<=? #\n c #\z) (integer->char (- (char->integer c) 13))]

[else c]))

(check-expect (rot13 #\5) #\5)

(check-expect (rot13 #\A) #\N)

(check-expect (rot13 #\N) #\A)

(check-expect (rot13 #\a) #\n)

(check-expect (rot13 #\n) #\a)

❀rot13string: produce new string by applying rot13 to each character of s

(define (rot13string s)

  (list->string

   (map rot13

        (string->list s))))

(check-expect (rot13string "Hello!")

              (list->string (map rot13 (string->list "Hello!"))))

ROT13

❤ Challenges I met this week

  ❀I didn’t know that every time we apply rot13 we have to type in “#/”before the number, so I failed to run the function correctly every time. I believe that next time I ll pay more attention to the definition of the function into details.

❤The test/quiz/assignment

The quiz this week is not about the content we learned this week. It’s still about the racket aggregate: how to decompose and reconstruct images. And I think that I did perfect in it.

The Wikipedia assignment is kind of hard for me, and it actually took me nearly two days to finish the “3-hour assignment” in part 2. Since reading the instructions of editing articles on the website and also looking for materials about the article are actually not easy for me as a result of my poor English. Feeling like the standard of judging whether we spent long enough time on the assignment is not that fair. But to get a good mark, what I can do is only to spend another two days to finish the next “4-hour assignment” for wiki3.

Yeah, csc104 requires a lot of reading and writing which makes it not like a computer science class to some extent. But maybe that is a good way for me to improve my English. Sigh anyway.

❤Feedback to others blogs
I read Emily Zhang's blog again this week lol. She stated what she had learned this week and it was a really long blog. So I left a comment: 
"Seems that you have learned a lot from this week lectures :D"