CISC181 1.25pm 2/20 P. Conrad Lecture Notes



Pointers and Addresses are just like arrays

Think of Memory as one big array with about 4 billion elements

To be precise: two to the 31st power minus 1 elements (about 4 billion)


 31
2   - 1


Before we can truly understand this or investigate it in code,
we need to understanding binary, octal, hexadecimal and decimal.


So:

 38 base 10 is _______________ base 2

 64  32   16   8  4  2  1
 0   1     0   0  1  1  0 

 13 base 16 is ___________  base 2

 1x16 + 3x1 =  19 base 10

   1     3  base 16
 0001  0011  base 2   answer is 0001 0011

  equally valid answer: 00010011

  equally valid answer: 10011

Practice these at:

 http://www.udel.edu/CIS/105/pconrad/05F/examInfo/E03_practiceQuiz/quiz2.html

 22 base 8 is ___     010 010 ____________ base 2 which is _________ base 10

   0 x 2^5 + 1 * 2^4 + 0 * 2^3 + 0 * 2^2 + 1 * 2^1 = 
            16 + 2 = 18

 2 * 8^1 + 2 * 8^0 = 2 * 8 + 2 = 16 + 2 = 18



 B15 base 16 is __  1011 0001 0101   ____  base 2


Now:
   1100 0011 1010 0111 0001 1111 1110 0101

    c    3    a     7   1     f    e   5


   0110 1001

     6   9


   0000 0001

     0    1

   0100 0010

     4    2


   1010  1011

    a      b

   1111  1110
     f     e


   1100  1101
    c      d