---
tags:
  - C
---

# Arrays in C

To declare an array in C, you must specify:

- the data type of the variables it will store
- the size (in square brackets)
- the array elements (in curly brackets)

Thus:

```c
int some_numbers[3] = {1, 2, 3};
```

> Array element individuation is the same as JavaScript, as is a standard `for`
> loop.

## Calculating the length of an array

Determining the length of an array is a fairly involved process compared to
higher-level languages. The process:

- Get the size of the array **in bytes**
- Divide this by the size of the first array element

So:

```c
int some_numbers[3] = {1, 2, 3};
int length = sizeof(some_numbers) / sizeof(arr[0]) // 3
```

What is happening under the hood:

The array has three `int` values. The normal byte size for a single `int` is 4
bytes (32 bits). 4 x 3 is 12. 12/4 is 3.