Which comes first in a 2D array, rows or columns?

Question

When creating a 2D array, how does one remember whether rows or columns are specified first?

Accepted Answer

Java specifies arrays similar to that of a "row major" configuration, meaning that it indexes rows first. This is because a 2D array is an "array of arrays".

For example:

```
int[ ][ ] a = new int[2][4];  // Two rows and four columns.

a[0][0] a[0][1] a[0][2] a[0][3]

a[1][0] a[1][1] a[1][2] a[1][3]
```

It can also be visualized more like this:

```
a[0] ->  [0] [1] [2] [3]
a[1] ->  [0] [1] [2] [3]
```

The second illustration shows the "array of arrays" aspect. The first array contains `{a[0] and a[1]}`, and each of those is an array containing four elements, `{[0][1][2][3]}`.

TL;DR summary:

```
Array[number of arrays][how many elements in each of those arrays]
```

For more explanations, see also Arrays - 2-dimensional.

Which comes first in a 2D array, rows or columns?

Solution

Problem

Related problems