# Arrays — C Programming

Source: https://www.geekswithgeeks.com/en/c/c-arrays

> A fixed-size sequence of same-typed values, in 1D and beyond.

## One name, many slots

An **array** stores a fixed number of values of the same type under one name, indexed from `0`. `int scores[5];` reserves room for 5 ints.

## Declare, initialise, index

Indexes run from `0` to `length - 1`. Reading past the end is **undefined behavior**, not a safe error.

```c
int nums[5] = {10, 20, 30, 40, 50};
printf("%d\n", nums[0]);   // 10
printf("%d\n", nums[4]);   // 50

for (int i = 0; i < 5; i++) {
    printf("%d ", nums[i]);
}
```

Output:

```
10
50
10 20 30 40 50
```

## Multi-dimensional arrays

A 2D array is an array of arrays — think of it as a grid with rows and columns.

```c
int grid[2][3] = {
    {1, 2, 3},
    {4, 5, 6}
};
printf("%d\n", grid[1][2]); // row 1, col 2
```

Output:

```
6
```

## sizeof reveals total bytes

`sizeof(nums)` gives the array's total bytes, not element count. Use `sizeof(nums) / sizeof(nums[0])` for element count.