---
id: seminar-03
title: 3rd seminar
description: |
  Select sort implementation on arrays.
---

:::caution

Deadline for the submission of the bonus is **March 16th 24:00**.

:::

:::tip

In case you have any questions, feel free to reach out either by email, Discord
or just by submitting an issue [here](https://gitlab.fi.muni.cz/xfocko/kb/-/issues/new).

:::

This assignment has two versions. For the light version you can get 1.5 K₡. For
the _full fat_ 3 K₡. **You can choose only one of them**.

To both of them you are given some basic tests. You can also have a look at the
code used by the tests and use it to your advantage.

Details can be found in the doxygen comments included in the source files.

## Light version (`main_light.c`)

[Source](pathname:///files/pb071/bonuses/03/main_light.c)

For the light version you have 3 functions to finish:

1. `swap` - that swaps two ints passed by pointers.
2. `maximum` - that returns index of the biggest `int` in the array.
3. `select_sort` - that sorts passed array using Select Sort.

## Full fat version (`main.c`)

[Source](pathname:///files/pb071/bonuses/03/main.c)

For the full fat version you have 4 functions to implement:

1. `swap` - that swaps two variables passed by pointers.
2. `maximum` - that returns index of the biggest element in the array using the
   comparator.
3. `select_sort` - that sorts passed array using Select Sort.
4. `int_comparator` - that is used for generic sort and maximum

To 2nd and 3rd function you are given a pseudocode that you can use to implement
it.

:::tip Function pointers

In the skeleton of the “full fat” version you might have noticed a weird type
signature of both the `maximum` and `select_sort` functions. Those functions get
passed a _function pointer_ to the comparator that you use for comparing the
respective elements in the passed in array.

If we take the parameter from one of the functions from the skeleton:
```c
int (*comp)(const void *, const void *)
```

`comp` is a function pointer to a function that takes two pointers of unspecified
type, i.e. pure address to the memory (you don't know what stored in there), and
returns an `int`.

You can pass the function by simply using its name. (There is no need to use `&`
to get its address.) And you can also call the function by “calling” the function
pointer, e.g. `comp(left, right)`.

:::

## Submitting

For submitting the bonus assignment you can follow the same procedure as for
submitting the homeworks, that is:

1. On branch `main` add the provided skeleton.
2. Checkout new branch `seminar-bonus-03`.
3. Add your solution to the newly created branch.
4. Create a MR to the `main` branch with me (`@xfocko`) as the reviewer.

:::tip Directory structure for bonuses

Ideally create a directory `seminar-bonuses` in the root of your repository with
bonuses in their own subdirectories.

Structure of your repository can look like this:
```
.
├── bonuses
│   └── seminar-03
├── hello
├── hw01
├── hw02
├── seminar-01
├── seminar-02
└── seminar-03
```

or

```
.
├── bonus-seminar-03
├── hello
├── hw01
├── hw02
├── seminar-01
├── seminar-02
└── seminar-03
```

Structure of the bonuses is entirely up to you, just keep it consistent.

:::