CSC161 2010F, Class 15: Pause for Breath

Overview:
* Thinking about assignment 4

Admin:
* We will have a moment of silence at the beginning of class for the 
  International Day of Peace.
* Debriefing on Town Hall Discussions.
  * Shared governance vs. self governance
  * More authoritarian than expected
  * Is civility an issue for students?
  * What did he say self-governance is: We give you the right to make
    some decisions about yourselves in prepration for you becoming
    citizens.
    * In the evening session, it sounded like he felt it needed review,
      just like any other aspect of the College.
* Reading for tomorrow: K&R 3.4.
* Advance notice: Your class mentor will conduct a review session 
  on Friday.
* Are there questions on Assignment 4?

Where do we begin on assignment 4?

* In general
  * Put foam padding on your head before banging it against things
  * Break the problem into smaller parts
  * Look at things we've done in class
  * Look at recent readings and stuff for basic operations

* For C like problems
  * Use man (may not be helpful for this particular assignment)
  * Look at K&R for similar examples
  
* Part 1
  * Problem: showintbits: Printing out the bits in an integer
  * Smaller parts:
    * Printing one bit
      * Printing the rightmost bit
      * One strategy (please don't use): Use modulus
        * (Printing any value)
    * Repeat it for each bit
  * Helpful knowledge:
    * Each bit corresponds to 2^kths power (rightmost is 2^0, next
      is 2^1, next is 2^2)
    * We know how to move bits left and right with <<, >>
    * Bitwise & can be useful
      0 & 0 is 0
      0 & 1 is 0
      1 & 0 is 0
      1 & 1 is 1
      so 1 & anything is that thing
      so 0 & antyhing is 0
      Start with the pattern 00000000000000000000000000000001 and
        bitwise and it with x, you get lots of 0s followed by the
        rightmost bit of x
  * Putting it together
    * Loop 32 times (for each bit), with k running from 31 down to 0
      print the bit at position k

* Part 1, continued
  * How do we print the rightmost bit?
    if ((i % 2) == 0)
      printf ("0");
    else
      printf ("1");

  * if ((i & 0x1) == 1)
      printf ("0");
    else
      printf ("1");
* How does that help in our loop?
  After we print the current bit, we can shift the bit pattern left 
    every time

* Part 2
  * Problem: 
  * Smaller parts:
  * Helpful knowledge: