help2002

It's UWAweek 47

help2002

This forum is provided to promote discussion amongst students enrolled in CITS2002 Systems Programming.
Please consider offering answers and suggestions to help other students! And if you fix a problem by following a suggestion here, it would be great if other interested students could see a short "Great, fixed it!" followup message.

Displaying the 11 articles in this topic

Showing 11 of 828 articles.
Currently 97 other people reading this forum.

UWA week 34 (2nd semester, week 5) ↓

mid-semester test Q10 of sample test (all 11)

2:09pm Mon 19th Aug, ANONYMOUS

for line C, it is: for(int i=0 ; i<N ++i){ ... } seems the answer should be line A. But is it okay that it doesn't have a semicolon after i<N?

mid-semester test Q10 of sample test (all 11)

4:31pm Mon 19th Aug, ANONYMOUS

Line A is valid; the syntax char array[N]; declares an array named "array" and allocates enough memory for N-many chars to be stored in the array, (see here).

There's definitely a syntax error in line C: there's no semicolon after i<N, so the compiler considers i<N ++i to be a whole expression, which is invalid.

mid-semester test Q10 of sample test (all 11)

4:37pm Mon 19th Aug, Christopher M.

ANONYMOUS wrote:

Line A is valid; the syntax char array[N]; declares an array named "array" and allocates enough memory for N-many chars to be stored in the array, (see here).

There's definitely a syntax error in line C: there's no semicolon after i<N, so the compiler considers i<N ++i to be a whole expression, which is invalid.

I'm afraid both of your points are incorrect. Please see: https://secure.csse.uwa.edu.au/run/help2002?p=np&opt=B72

mid-semester test Q10 of sample test (all 11)

4:52pm Mon 19th Aug, ANONYMOUS

Oh, I see, there's a semicolon after the N... oops. I'll be mindful of that in future.

When you say both your points, are you saying that for(int i=0 ; i<N ++i){ is valid syntax? Or are you talking about the response above mine?

Thanks for the response.

mid-semester test Q10 of sample test (all 11)

4:55pm Mon 19th Aug, ANONYMOUS
✅ content verified by our teaching staff

N is replaced with "10;" - so the syntax becomes valid.. for(int i=0; i<10; ++i)

mid-semester test Q10 of sample test (all 11)

4:55pm Mon 19th Aug, Christopher M.

ANONYMOUS wrote:

> When you say both your points, are you saying that `for(int i=0 ; i<N ++i){` *is* valid syntax?

It's certainly an error if you correctly perform the textual substitution for N . A couple of students have asked if this is a trick question - not really, misunderstandings about how the preprocessor works are reasonably common.

mid-semester test Q10 of sample test (all 11)

8:13am Wed 21st Aug, ANONYMOUS

How can the answer still be A when line A is valid and line C contains a syntax error?

mid-semester test Q10 of sample test (all 11)

8:15am Wed 21st Aug, Christopher M.

ANONYMOUS wrote:

> How can the answer still be A when line A is valid and line C contains a syntax error?

Line A is not valid, and line C does not contain a syntax error. Cut-paste-compile the code if you need to.

mid-semester test Q10 of sample test (all 11)

1:51pm Wed 21st Aug, ANONYMOUS

Wouldn't this mean that A and B are incorrect. Since we define N as 10; // which includes the semicolon. That means for A, Substitution: char array[10;]; The semicolon causes a syntax error here. For B, int x = 2 * 10;; This results in a double semicolon (;;), which is a syntax error. For C, I think that is okay for the semicolon to be before ++i Thanks!

mid-semester test Q10 of sample test (all 11)

2:01pm Wed 21st Aug, ANONYMOUS
✅ content verified by our teaching staff

Not sure if I am correct but the reason why B (int x = 2 * 10;;) is because it would take the second semicolon as an empty statement so it'll be read as int x = 2 * 10; ; which would not affect the program itself but will just look weird and isn't good practice

mid-semester test Q10 of sample test (all 11)

2:21pm Wed 21st Aug, Christopher M.

ANONYMOUS wrote:

> Not sure if I am correct but the reason why B (int x = 2 * 10;;) is because it would take the second semicolon as an empty statement so it'll be read as > int x = 2 * 10; > ; > which would not affect the program itself but will just look weird and isn't good practice

This is the correct reasoning.