Two-dimensional array initialization values

Question

I'm working on a program using arrays and I'm trying to figure out

First, with the following array declaration, what is the value stored in the scores[2][2] element?

int scores[3][3] = { {1, 2, 3} };

And also with this array declaration, what is the value stored in the scores[2][3] element?

int scores[5][5] = {5};

Could someone please explain this for me.

All unset values are set to 0 in this case.

juanchopanza
– juanchopanza

2014-12-02 11:39:18 +00:00
Commented Dec 2, 2014 at 11:39 — juanchopanza
– juanchopanza, Commented Dec 2, 2014 at 11:39
Try it. Three lines of code...

Pete Becker
– Pete Becker

2014-12-02 15:01:47 +00:00
Commented Dec 2, 2014 at 15:01 — Pete Becker
– Pete Becker, Commented Dec 2, 2014 at 15:01

Yu Hao · Accepted Answer · 2014-12-02 11:39:28Z

6

int scores[3][3] = { {1, 2, 3} };

is equivalent to:

int scores[3][3] = { {1, 2, 3}, {0, 0, 0}, {0, 0, 0}};

The other one is similar. You know the answer.

answered Dec 2, 2014 at 11:39

Yu Hao

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4 Comments

michael m Over a year ago

I got that part, they only thing I wasn't sure about is identifying the value.

Yu Hao Over a year ago

@michaelm If you got this part, the rest is easy, the only thing I think worth mentioning is indexing starts from 0.

michael m Over a year ago

So since I have a 2D array (a row/column grid), but only specified the first line, so the rest get initialized to zero so I should expect the code to write zero right?

Yu Hao Over a year ago

@michaelm As long as there's an initializer, all the elements not explicitly initialized are initialized to 0. For instance, int scores[3][3] = {} sets all elements to 0.

Jonathan Mee · Accepted Answer · 2014-12-02 11:59:41Z

3

Array indexing is zero-based.

Which means that for: int foo[3] = {10, 20, 30};

foo[0] is 10
foo[1] is 20
foo[2] is 30

For multidimensional arrays, you should think of them as arrays of arrays.

So this would create an array containing two int[3]s: int foo[2][3] = {{10, 20, 30}, {40, 50, 60}};

foo[0][0] is 10
foo[0][1] is 20
foo[0][2] is 30
foo[1][0] is 40
foo[1][1] is 50
foo[1][2] is 60

C supports partial initialization. In which it will default all non initialized values to 0.

So if you were to do this: int foo[3] = {5};

foo[0] is 5
foo[1] is 0
foo[2] is 0

Similarly for a multidimensional array: int foo[2][3] = {5};

foo[0][0] is 5
foo[0][1] is 0
foo[0][2] is 0
foo[1][0] is 0
foo[1][1] is 0
foo[1][2] is 0

answered Dec 2, 2014 at 11:59

Jonathan Mee

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1 Comment

Jonathan Mee Over a year ago

@michaelm Don't forget to accept either Yu Hao's answer or my answer if one of them answered your question.

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