Question

Question 3: What do the following vim commands do in command mode?

ZZ

:w!

i

dd

x

yy

p

Question 4: Review the following code. If you were to print out all the dereferenced values of the three pointer variables and the array, what is the output?

(note: if possible explain how the output changed.)

int array[] = { 30, 40, 50, 60, 70, 80 };

int *ptrA = array;

int *ptrB = ptrA + 4;

int *ptrC = ptrB--;

array[ 1 ] = 2;

*ptrB = *ptrC - 2;

*ptrC = 100;

array[ 3 ] = *ptrA++;

ptrC = ptrB + 2;

Answer 1

1)

ZZ

Write current file, if modified, and exit.

:W!

Write the current file and exit always.

i

Insert text before the cursor [count] times.

dd

Delete [count] lines

x

Delete [count] characters before the cursor.

yy

it copies the line for you to put into the file immediately. This command "yanks" the current line into the vi general buffer.

p

it paste the previously deleted text after the cursor.

2)

usage of 'int' here is not the correct method.

using 'int'  ("%d")  with pointers is incorrect and invokes undefined behavior.

Pointers should be printed with %p not %d because the number might be too big , so it became overflow.

if you print with "%d" then the values are:

array values are: -2112859744
-2112859740
-2112859736
-2112859732
-2112859728
-2112859724

ptr A -2112859740
ptr B -2112859732
ptr C -2112859724