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 11272012, 08:22 PM #1Member
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What does this program line print out? (tables (or matrices?))
Here's a question that I need to know the answer for. What does this program print out at the end?
As I've understood it, the values mx should get at [0], [1] and [2] are 0, 1 and 4 on both of those.
I've figured a whole lot of ways to calculate sum, for example (0+4+0) + (4+4+1) + (9 + 4+4), but none of those add up.
Java Code:int[][] mx = new int[3][3]; for (int i = 0; i < 3; i++) { for (int j = 0; j < 3; j++) { mx[i][j] = i * j; } } int sum = 0; for (int i = 0; i < 3; i++) { sum = sum + mx[2][i]; } System.out.println(sum);
So two questions: what number does it produce and why?
Thanks. Your help is very much appreciated.
 11272012, 08:42 PM #2Senior Member
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Re: What does this program line print out? (tables (or matrices?))
You have a 3x3 matrix
[x, x, x]
[x, x, x]
[x, x, x]
which is filled by your first loops.
i and j are 0 to 3. so you will fill the first line, than the second and the third. so, for the first line, it will be 0, 0 * everything is 0, so the first line is fully filled with 0
>
[0, 0, 0]
[x, x, x]
[x, x, x]
for the second line, i will be 1, j will be 0,1 and 2.
1*0 = 0
1*1 = 1
1*2 = 2
>
[0, 0, 0]
[0, 1, 2]
[x, x, x]
the last line is yours...you will get it, i`m sure :)
so, in the loop at the lines 8  10, it will sum up only the values from "column" 2
0+2+x = ??
I hope it helps you
 11272012, 08:43 PM #3
Re: What does this program line print out? (tables (or matrices?))
This sounds like a homework question. Asking us what it does is pretty much defeating the purpose of the assignment, isn't it?
Trace through it with a piece of paper and a pencil. What do you expect to happen?
Then put together a little program that tests that assumption. Did it match? If not, step through it with a debugger to figure out what the difference is.How to Ask Questions the Smart Way
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 11282012, 07:33 PM #4Member
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Re: What does this program line print out? (tables (or matrices?))
Thanks eRaaaaa! Got it right, finally.
KevinWorkman, quilty as charged. Tried to figure it out for like 20 minutes until I gave up. Not a big deal really, it was one of a set of 10 questions, each correct answer giving one point. And at this course we can gain a maximum of 1400 or so points. A perfectionist in me though didn't want to leave it hanging :D
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