CS208 Introduction to Computer Systems
Friday, 3 April 2026

+ Quiz on Monday, April 6
- bitwise operators (|, &, ~, ^)
- numbers will be represented as hexadecimal
- Example question:

    Given 8-bit numbers a = 0xE5 and b = 0x3C,
    express ~a, a&b, and a|b as 2-digit hexadecimal numbers.

+ Today: miscellaneous stuff

+ LAB items
- worth a few points (between 2 and (rarely) 5; compare to quizzes 2-3)
- due the day we do them in class
- "good-faith effort" scoring

+ Bitwise operators
- <<, >>, multiplication, and division
- what makes "print_integer_in_binary" tricky
    - two strategies
- "turning on bit N", "turning off bit N"
- "masking out a portion of an int"

+ Today's assignment questions

+ Misc
- remember this, which often applies: "you can just try it and see what happens"
    (of course, you want to follow that up with "why?")
- assert
- byte-counter.c and its more complicated pal

+ Monday's assignment

+ Null-terminated strings in C
- the idea
- what's this "char *" thing?

+ Coming up
- negative integers
- characters: ASCII, Unicode, UTF-8, UTF-16
- (try to find half a day for float--i.e., real numbers)
- more on strings


=====
#include <stdio.h>

int main() {
    int a = 0xE5;
    int b = 0x3C;

    printf("0x%x\n", a | b);
    printf("0x%x\n", a & b);
    printf("0x%x\n", a ^ b);
    printf("0x%x\n", ~a);

    return 0;
}