I don't really understand those multidimensional arrays

Question

please, can someone explain me why the two of arrays [0][2] together are equal to 42 and how we calculate them later in System.out.printIn(x); as soon as int x=myArr[1][0];

public class Program {
public static void main(String[] args) {
int[ ][ ] myArr = { {1, 2, 3}, {4}, {5, 6, 7} };
myArr[0][2] = 42;
int x = myArr[1][0];

System.out.println(x);
}
}
https://code.sololearn.com/cKs8tGxoDBUj/?ref=app

Answer 1

I agree with you, multidimensional arrays can get confusing, especially when it's more than 2D (two dimensional) for me. There is a simple way to understand it better though and that's by picturing it.

A two dimensional array can be pictured as a table, a table that has rows and columns. Let's create a 3x3 table quickly to demonstrate this.

Example (Java):

0 1 2
___________
0 l_a_l_b_l_c_l
1 l_d_l_e_l_ f_l
2 l_g_l_h_l_ i_l

-The table above is a 3x3 table, meaning it has 3 rows and 3 columns
-Each cell of the table is filled with a different letter
-If I want to identify where a letter is, I would need two coordinates right? A coordinate for rows and a coordinate for columns
-So let's say I want to get letter "a" then it would be in row(0) and in column(0) right?
-Let's try to get letter "f", it would be in row(1) in column(2) right?
-So this is really the simplest way to understand multidimensional arrays by picturing it.
-Let's now put this in a coding perspective, let's say I want to change the letter "f" to letter "z" then it would look something like this:

table[1][2] = "z";

-Does it look simpler now with my explanation or are you still confused? Let me know.

Answer 2

FAQ...
https://www.sololearn.com/discuss/230542/?ref=app

Answer 3

In your code here you have defined a matrix called myArr with 3 rows and 3 columns which you can visualize as:
1 2 3
4
5 6 7

The statement myArr[0][2] = 42 assigns value .42 to 0th row and 2nd col so ur matrix now becomes
1 2 42
4
5 6 7

Answer 4

Similarily myArr[1][0] means element at 1st row 0th col that is 4 in your matrix. This yor are assigning to x and printing.
So the output of your code is 4

Answer 5

This is Solution : Don't forget to Upvote
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using System;
using System.Collections.Generic;
using System.Diagnostics;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

namespace SoloLearn
{
class Program
{
static void Main(string[] args)
{
int[,] num = { { 1, 2, 3 }, { 4, 5, 6 }, { 7, 8, 9 } };

//your code goes here
for(int i=0; i<3;i++)
{
for(int j=0;j<3;j++)
{

Console.WriteLine(num[i,j]);

}
}
}
}
}

Answer 6

Gavin your explanation is so easy to understand, at first i didn't knew that it refer to a matrix cause i knew that the matrix starts with [1][1] not [0][0].
Thanks a lot guys, i really appreciate.

Answer 7

i already do matrix at math class but those doesn't seem to look like that ones.
it is a little complicated.
But thank you for helping me. :)

Answer 8

Thanks Tashi N, You are the best. :)