Section 9.7
Review Questions
A pointer example
  1. Which of the following C declarations creates a pointer? 
               int *m;
               int n;
answer...
int *m;
  1. What is the meaning of the asterisk in the following C code? 
               z = *m;
answer...
use m's value as a memory address for load; don't use m's value directly as data
  1. What are pointers, really? 
          a.  memory addresses
          
          b.  pieces of data
          
          c.  complete arrays
          
          d.  special machine instructions?
answer...
a. memory addresses
  1. Why is there not much difference in machine language between arrays and pointers?
answer...
because they all use indirect addressing
  1. In C, how does the initial pointer get created and put into a pointer variable? Write the line of code that puts the base address of the source block into pointer p1.
answer...
p1 = &array[0];
  1. Some computers have machine instructions which can do address calculations while loading the data into the accumulator, thereby circumventing the need for 3 or 4 separate instructions. What is the downside of this?
answer...
the computer's control unit is much more complicated
  1. Why can characters be manipulated by the CSC-1 by merely shuffling integers around between memory and the registers? (HINT: Remember ASCII?)
answer...
because there really are no characters! They are all just small numbers.
  1. Write a short chunk of CSC-1 code to get the integer pointed at by p and store it into the A register. Do not change p.
answer...
      LOD   P
      A2S
      LDS
  1. Write a short chunk of CSC-1 code to get the integer pointed at by p, add 1 to it, and store it back into memory at the same location. Do not change p. (harder)
answer...
      LOD   P
      A2S
      LDS
      ADD   ONE
      STS
...
ONE:  NUM   1