CODEWITHSUNDEEP
javaarrays
Isaac Adni
Isaac Adni

Reputation: 841

Difference between array.length and array[0].length in a multi-dimensional array?

When I create a new multi-dimensional array (in this case an array of objects)

public Block[][] block = new Block[50][70];

What is the difference between:

block.length

and

block[0].length

and then what is

block[1].length

Upvotes: 0

Views: 24811

Answers (4)

micronyks
micronyks

Reputation: 55453

here you have two dimensional array. it has 50 rows and 70 columns. it means...

about block array... block array will look like (row & column wise)

block=   0...1...2...3...4...SO..ON...69
         1
         2           50
         3
         4
         5
         SO..ON
         ..
         ..
         49

Now you are having tabular format of block array. now lets say I want to get value of block[2][3]... it means 2th row and 3rd column which is 50 as shown above.

block.length total rows of Block array.

block[0] is referring to 0th row of Block array and so block[0].length gives you columns associated with 0th row which 70 so ans would be 70 (Note:total count)....

and so on....

Upvotes: 2

Bohemian
Bohemian

Reputation: 425458

If you think of Block[][] as being rows and columns of Block, and each row being a Block[] of columns, and an array of rows would be a Block[][], then:

block.length // the number of rows
block[0].length // the number of columns on row 0
block[1].length // the number of columns on row 1
// etc

Upvotes: 7

Shahar
Shahar

Reputation: 1677

block.length is the number of rows. block[0].length is the number of columns in row 0. block[1].length should have the same value as block[0].length since it has the same number of columns as the first row.

Upvotes: 1

gexicide
gexicide

Reputation: 40128

What do you expect? You have a multi dimensional array. Thus, there is more than one dimension. Each dimension has a length. With block.length you get the length of the first one (i.e. 50), with block[x].length, you get the length of the second one (i.e., 70).

Since you allocated your array like this, all block[x].length will be equal, no matter what you choose for x. However, you could have an array where the nested arrays have different lengths, then block[0].length might not be equal to block[1].length.

Upvotes: 2

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