Description
3 programs about C pointers need to be understood, like
3 questions Q1, Q2, and Q3:
Q1. ptr0.c (target variables: i, j, p, q, and r)
Q2. ptr1.c (target variables: p, q, and array x in main())
Q3. ptr2.c (target variables: i, j, and p in main())
Please use apply the 32-bit mode of GCC to compile code, e.g.,
gcc -m32 ptr0.c
To make sure the size of a pointer is 4 (bytes), try a test.c:
// test.c
#include <stdio.h
main() {
printf(“size of int * is %i\n”, sizeof(int *));
}
Run each of the pointer programs to see and get the output.
Like what’s illustrated during class sessions, and in textbook, draw a diagram with each of the variable memory location as a rectangle box, and follow the changes in the output to fill out the boxes as the program statements go.
I.e., Follow the sequence of code, draw results whenever a statement changes the contents of any locations, e.g., label addresses and fill out boxes whenever box contents get changed.
Example:
// here.c
#include <stdio.h
main() {
int a, b, *p; a b p
addr content addr content addr content
83357c8 [ ? ] 83357c4 [ ? ] 83357c0 [ ? ]
a = 5; [ 5 ] [ ? ] [ ? ]
p = &b; [ 5 ] [ ? ] [83357c4]
(and so on…)
}
Turn-in: hard copy, hand-written and drawn, or hand-drawn boxes mixed with computer printouts is OK.
How to login a Linux host:
Use your ECS network account and Windows “PuTTy” or Mac “terminal” app
to login one of the Linux hosts designated for our assignment usages.
e.g., Mac terminal command: ssh (your username)@atoz.ecs.csus.edu
From off campus you connect to host titan or athena first, then go to one of the assignment-working host with shell command: ssh (your username)@atoz (or sp1/2/3)
Shell command to edit program, e.g., vi my.c
Shell command to compile program: gcc -m32 my.c
Shell command to run program: a.out (or ./a.out if . is not in search path)
