Week 01 Weekly Exercises

Objectives

to practice the basics of Rust
to practice using Rust tools
to practice rust intro and algebraic types

Activities To Be Completed

The following is a list of all the markedactivities available to complete this week...

Mini-Grep
Multiverse
Carnival
DALL-E-RS
Picasso
Dealing with IO

The following practice activities are optional and are not marked, or required to be completed for the week.

None - all exercises this week are marked.

Preparation

Before attempting the weekly exercises you should re-read the relevant lecture slides and their accompanying examples.

Getting Started

Create a new directory for this week's exercises called lab01, change to this directory, and fetch the provided code for this week by running these commands:

mkdir lab01
cd lab01
6991 fetch lab 01

Or, if you're not working on CSE, you can download the provided code as a tar file.

Exercise:
Mini-Grep

You have been given a crate, mini_grep, which prints the first command-line argument.

Your task is to modify mini_grep/src/main.rs, such that it reads lines on standard input, printing each line back out if and only if the input line contains the command-line argument.

For example,

cd mini_grep
6991 cargo run -- foo
    Finished dev [unoptimized + debuginfo] target(s) in 0.00s
     Running `target/debug/mini_grep foo`
this line contains the text foo so it is printed
this line contains the text foo so it is printed
... but this line does not, so it is not printed

6991 cargo run -- hi
    Finished dev [unoptimized + debuginfo] target(s) in 0.00s
     Running `target/debug/mini_grep foo`
the pattern can appear inside a larger word: chicken!
the pattern can appear inside a larger word: chicken!

6991 cargo run -- HI
    Finished dev [unoptimized + debuginfo] target(s) in 0.00s
     Running `target/debug/mini_grep foo`
the pattern is case-sensitive: hi
Hi and hI don't work either
only HI will match this pattern
only HI will match this pattern

6991 cargo run -- 😂
    Finished dev [unoptimized + debuginfo] target(s) in 0.00s
     Running `target/debug/mini_grep foo`
oh and; emojis should work too 😂😂😂
oh and; emojis should work too 😂😂😂
and they follow the same rules: 😃 🌍 🍞 🚗

The documentation for the contains method may be useful.

The documentation for if expressions may be useful.

The documentation for loop expressions may be useful.

The documentation for the args function may be useful.

You can assume that if read_line leaves your input string empty (is_empty) then your program has reached end of input and should exit.

When you think your program is working, you can use autotest to run some simple automated tests:

6991 autotest

When you are finished working on this exercise, you must submit your work by running give:

6991 give-crate

The recommended due date for this exercise is Week 2 Wednesday 21:00:00.

You must run give before Week 10 Friday 17:00:00 to obtain the marks for this exercise. Note that this is an individual exercise; the work you submit with give must be entirely your own.

Exercise:
Multiverse

Across the broad range of the multiverse, there are an infinite number of universes! These universes however follow a pattern, allowing us to write code in order to output the details of a universe, given its id.

You have been given a crate, multiverse, which does not compile!

Your task is to modify the given structure, get_universe_details function and the noted areas of the main function, inside multiverse/src/main.rs, such that it loops through id's of 1-15, and prints out the universe details of the universe with that ID.

The universe lookup follows some basic rules:

If the universe id is divisible by 3 - then that universe is the star wars universe, where the rebels won and the population is the max number that a u32 can fit!
If the universe id is divisible by 5 - then it is the miraculous ladybug universe, where the villian Hawk Moth won, leaving the universe with a population of 22.
Finally, if the universe id is divisible by both 5 and 3 - then it is the Stardew Valley universe, where the evil Jojo Corp won, leaving a population of only one!

Your program should match the following example

cd multiverse
6991 cargo run
    Finished dev [unoptimized + debuginfo] target(s) in 0.00s
     Running `target/debug/multiverse`
Universe with id 1 is unknown
Universe with id 2 is unknown
Universe with id 3 is called Star Wars, won by The Rebellion and has a population of 4294967295
Universe with id 4 is unknown
Universe with id 5 is called Miraculous, won by Hawk Moth and has a population of 22
Universe with id 6 is called Star Wars, won by The Rebellion and has a population of 4294967295
Universe with id 7 is unknown
Universe with id 8 is unknown
Universe with id 9 is called Star Wars, won by The Rebellion and has a population of 4294967295
Universe with id 10 is called Miraculous, won by Hawk Moth and has a population of 22
Universe with id 11 is unknown
Universe with id 12 is called Star Wars, won by The Rebellion and has a population of 4294967295
Universe with id 13 is unknown
Universe with id 14 is unknown
Universe with id 15 is called Stardew Valley, won by Jojo Corp and has a population of 1

Authors Note

The starter code is filled with errors - deliberately aimed to mimic the syntax of other languages. There are also lines of code that make zero sense in the context of Rust (e.g. having data inside a None on line 12).

This exercise can be challenging - feel free to ask on the course forum and/or discuss with your peers!

Completing this exercise should encourage the following:

Do you know the correct struct syntax?
Do you know how to return an option containing some data?
Familiarity with returning an expression
Using an if let to extract data from an Option
How to encode optiona data with the Option type

When you think your program is working, you can use autotest to run some simple automated tests:

6991 autotest

When you are finished working on this exercise, you must submit your work by running give:

6991 give-crate

The recommended due date for this exercise is Week 2 Wednesday 21:00:00.

You must run give before Week 10 Friday 17:00:00 to obtain the marks for this exercise. Note that this is an individual exercise; the work you submit with give must be entirely your own.

Exercise:
Carnival

Shrey and Tom are looking to go to the carnival! However, there is only one ticket 🥺

You have been provided a crate, carnival. Your task is to modify the main function in carnival/src/main.rs, and the move_ticket function, to make them go to the carnival.

Specifically, you should

Only change the main function from line 16 onwards
Implement the move_ticket function
Move the ticket that Shrey owns to Tom
Not use any concepts not yet taught (namely, borrowing)

This exercise aims to test your understanding of Rust's ownership system. Like most exercises, you can simply just print the right output, or do lots of .clone(), but this will not help you in future assignments or the final exam.

The output when completed, should look like:

cd carnival
6991 cargo run
    Finished dev [unoptimized + debuginfo] target(s) in 0.00s
     Running `target/debug/carnival`
SHREY ticket: None
TOM ticket: Some(Ticket)

Hint 1

Using the variable shrey_name as the value for the name field on line 21 won't work. Why not?

When we use the to_uppercase function earlier, we are moving the value of shrey_name into the function. The function did however return us a new value, perhaps we could use that?

If we try to use a value after it has been moved out of the scope - rust will throw a compile-time error.

The following link may be useful: ownership and functions

Does the same issue exist with tom_name?

Hint 2

We are trying to print out the fields of shrey and tom - but earlier, we moved both values into the move_ticket function!

The move_ticket function does return back the modified structures, but we are not using the return value. With the first move error, we fixed that by creating a new variable binding with the contents of the returned uppercase value (e.g. shrey_upper_name), and using that later on.

Could we do the same thing here, and create a binding for the return value of move_ticket?

Remember, you can destructure a tuple in assignment:

let (a, b, c, d) = tuple;

When you think your program is working, you can use autotest to run some simple automated tests:

6991 autotest

When you are finished working on this exercise, you must submit your work by running give:

6991 give-crate

The recommended due date for this exercise is Week 2 Wednesday 21:00:00.

You must run give before Week 10 Friday 17:00:00 to obtain the marks for this exercise. Note that this is an individual exercise; the work you submit with give must be entirely your own.

Exercise:
DALL-E-RS

In order to get started, you will need to create a Cargo project

You can do this by running the cargo new command in your terminal

6991 cargo new dall-e-rs
Created binary (application) `dall-e-rs` package

Your task is to create a simple Cargo project, in order to generate some art by outputting a 200 x 200 bmp image. This exercise enables you to practice using the cargo build system. It is manually marked, (practically any image that has some degree of effort will get full marks) and your submission will be uploaded to a course gallery later during week 2/3.

You should now have a Cargo package inside the dall-e-rs directory.

cd dall-e-rs
ls
Cargo.toml  src

The cargo project starts you off with a Cargo.toml file, which describes the project.

cat Cargo.toml
[package]
name = "dall-e-rs"
version = "0.1.0"
edition = "2021"

# See more keys and their definitions at https://doc.rust-lang.org/cargo/reference/manifest.html

[dependencies]

The dependencies section of the Cargo.toml file describes the dependencies of the project.

In this case we need to have a dependancy on the bmp crate (remember, a crate is what Rust calls an external library).

We can add this dependancy by running the following command:

6991 cargo add bmp
    Updating crates.io index
      Adding bmp v0.5.0 to dependencies.

You can search for Rust libraries (we call them "crates") on the Rust community crate registry: https://crates.io/. To view the documentation for a particular crate, you can visit https://docs.rs/<crate>/, where <crate> is the name of the crate.

For example, the documentation for the bmp crate can be found at https://docs.rs/bmp/.

Cargo also creates a src directory, which contains the source code for the project. This directory starts with a main.rs file, which is the entry point for the project.

ls src
main.rs
cat src/main.rs
fn main() {
    println!("Hello, world!");
}

You write your program in here!

To compile your project, you can run the following command:

6991 cargo build
    Updating crates.io index
   Compiling byteorder v1.4.3
   Compiling bmp v0.5.0
   Compiling dall-e-rs v0.1.0 (/tmp/tmp.CCQoWnQuRt/dall-e-rs)
    Finished dev [unoptimized + debuginfo] target(s) in 1.46s

Your code will be compiled into an executable binary, located in the newly created target directory.

ls
Cargo.lock  Cargo.toml  src  target
ls target
CACHEDIR.TAG  debug
ls target/debug
build  deps  examples  incremental  dall-e-rs  dall-e-rs.d
./target/debug/dall-e-rs
Hello, world!

Instead of writing 6991 cargo build, followed by ./target/debug/dall-e-rs each time you want to run your program, you can simply use the 6991 cargo run command.

6991 cargo run
    Finished dev [unoptimized + debuginfo] target(s) in 0.00s
     Running `target/debug/dall-e-rs `
Hello, world!

Now it is your turn! Think of a fun idea for a simple piece of art, and then write it in the src/main.rs file. Your code should generate a single file, which should have a .bmp extension.

Don't forget to test your code along the way with the cargo run command.

When you are finished working on this exercise, you must submit your work by running give:

6991 give-crate

The recommended due date for this exercise is Week 2 Wednesday 21:00:00.

You must run give before Week 10 Friday 17:00:00 to obtain the marks for this exercise. Note that this is an individual exercise; the work you submit with give must be entirely your own.

Exercise:
Picasso

Your task is to write a small command-line utility, that will read in a list of file names (.bmp files) and output their representation to the terminal.

Your program will only be given either valid BMP files, consisting of RED, LIME, BLUE and WHITE pixels, or a malformed file (including, for example, a filepath to a file that does not exist). These constants can be found in bmp::consts (i.e, the consts module of the bmp crate).

If your program is given a valid BMP file, it should output the following:

6991 cargo run -- path/to/shreys_art.bmp
    Finished dev [unoptimized + debuginfo] target(s) in 0.00s
     Running `target/debug/picasso path/to/shreys_art.bmp`
===== ../../files.cp/shreys_art.bmp =====
R W W W W W W W W W W W W W B G W R W W R W W R W W R W W R 
W R W W W W W W W W W W W W B G R W W R W W R W W R W W R W 
W W R W W W W W W W W W W W B G W W R W W R W W R W W R W W 
W W W R W W W W W W W W W W B G W R W W R W W R W W R W W R 
W W W W R W W W W W W W W W B G R W W R W W R W W R W W R W 
W W W W W R W W W W W W W W B G W W R W W R W W R W W R W W 
W W W W W W R W W W W W W W B G W R W W R W W R W W R W W R 
W W W W W W W R W W W W W W B G R W W R W W R W W R W W R W 
W W W W W W W W R W W W W W B G W W R W W R W W R W W R W W 
W W W W W W W W W R W W W W B G W R W W R W W R W W R W W R 
W W W W W W W W W W R W W W B G R W W R W W R W W R W W R W 
W W W W W W W W W W W R W W B G W W R W W R W W R W W R W W 
W W W W W W W W W W W W R W B G W R W W R W W R W W R W W R 
W W W W W W W W W W W W W R B G R W W R W W R W W R W W R W 
G G G G G G G G G G G G G G B G B B B B B B B B B B B B B B 
B B B B B B B B B B B B B B G B G G G G G G G G G G G G G G 
W R W W R W W R W W R W W R G B R W W W W W W W W W W W W W 
R W W R W W R W W R W W R W G B W R W W W W W W W W W W W W 
W W R W W R W W R W W R W W G B W W R W W W W W W W W W W W 
W R W W R W W R W W R W W R G B W W W R W W W W W W W W W W 
R W W R W W R W W R W W R W G B W W W W R W W W W W W W W W 
W W R W W R W W R W W R W W G B W W W W W R W W W W W W W W 
W R W W R W W R W W R W W R G B W W W W W W R W W W W W W W 
R W W R W W R W W R W W R W G B W W W W W W W R W W W W W W 
W W R W W R W W R W W R W W G B W W W W W W W W R W W W W W 
W R W W R W W R W W R W W R G B W W W W W W W W W R W W W W 
R W W R W W R W W R W W R W G B W W W W W W W W W W R W W W 
W W R W W R W W R W W R W W G B W W W W W W W W W W W R W W 
W R W W R W W R W W R W W R G B W W W W W W W W W W W W R W 
R W W R W W R W W R W W R W G B W W W W W W W W W W W W W R

If your program is given a malformed BMP file, it should output Error!, followed by the debug representation of the error message. e.g. - consider the following error variation, where an invalid compression type is given:

6991 cargo run -- path/to/bad_compression.bmp
    Finished dev [unoptimized + debuginfo] target(s) in 0.00s
     Running `target/debug/picasso ../../files.cp/bad_compression.bmp`
===== path/to/bad_compression.bmp =====
Error! BmpError { kind: UnsupportedCompressionType, details: "RLE 8-bit" }

Multiple files should be seperated by equals and the filename, e.g.:

6991 cargo run -- path/to/bad_compression.bmp path/to/shreys_art.bmp
    Finished dev [unoptimized + debuginfo] target(s) in 0.44s
     Running `target/debug/picasso path/to/bad_compression.bmp path/to/shreys_art.bmp`
===== path/to/bad_compression.bmp =====
Error! BmpError { kind: UnsupportedCompressionType, details: "RLE 8-bit" }
===== path/to/shreys_art.bmp =====
R W W W W W W W W W W W W W B G W R W W R W W R W W R W W R 
W R W W W W W W W W W W W W B G R W W R W W R W W R W W R W 
W W R W W W W W W W W W W W B G W W R W W R W W R W W R W W 
W W W R W W W W W W W W W W B G W R W W R W W R W W R W W R 
W W W W R W W W W W W W W W B G R W W R W W R W W R W W R W 
W W W W W R W W W W W W W W B G W W R W W R W W R W W R W W 
W W W W W W R W W W W W W W B G W R W W R W W R W W R W W R 
W W W W W W W R W W W W W W B G R W W R W W R W W R W W R W 
W W W W W W W W R W W W W W B G W W R W W R W W R W W R W W 
W W W W W W W W W R W W W W B G W R W W R W W R W W R W W R 
W W W W W W W W W W R W W W B G R W W R W W R W W R W W R W 
W W W W W W W W W W W R W W B G W W R W W R W W R W W R W W 
W W W W W W W W W W W W R W B G W R W W R W W R W W R W W R 
W W W W W W W W W W W W W R B G R W W R W W R W W R W W R W 
G G G G G G G G G G G G G G B G B B B B B B B B B B B B B B 
B B B B B B B B B B B B B B G B G G G G G G G G G G G G G G 
W R W W R W W R W W R W W R G B R W W W W W W W W W W W W W 
R W W R W W R W W R W W R W G B W R W W W W W W W W W W W W 
W W R W W R W W R W W R W W G B W W R W W W W W W W W W W W 
W R W W R W W R W W R W W R G B W W W R W W W W W W W W W W 
R W W R W W R W W R W W R W G B W W W W R W W W W W W W W W 
W W R W W R W W R W W R W W G B W W W W W R W W W W W W W W 
W R W W R W W R W W R W W R G B W W W W W W R W W W W W W W 
R W W R W W R W W R W W R W G B W W W W W W W R W W W W W W 
W W R W W R W W R W W R W W G B W W W W W W W W R W W W W W 
W R W W R W W R W W R W W R G B W W W W W W W W W R W W W W 
R W W R W W R W W R W W R W G B W W W W W W W W W W R W W W 
W W R W W R W W R W W R W W G B W W W W W W W W W W W R W W 
W R W W R W W R W W R W W R G B W W W W W W W W W W W W R W 
R W W R W W R W W R W W R W G B W W W W W W W W W W W W W R

This is a pretty beefy exercise, break it down into steps! Make sure to look at the below documentation, especially the examples!

Note: LIME should display as G

You should aim to do this exercise without borrowing, or other advanced concepts that have not yet been taught. If you are unsure, ask on the course forum or in consultations.

The documentation for the match keyword may be useful.

The documentation for the result type may be useful.

The documentation for the bmp crate may be useful.

The documentation for the get_pixel method may be useful.

The documentation for the args function may be useful.

Click to reveal further hint

You'll roughly need the following approach:

For all commandline arguments after the first:
Use bmp::open to open the file
Match on the result from bmp::open (according to the documentaion, this is a Result - so Ok or Err)
Loop through all coordinates as shown in the example
Match on the return of get_pixel, and print out the correct character
If the x coordinate is at the end of the row (get_width() ), then you will need to print an empty line (so that it looks like a new row on the output)

When you think your program is working, you can use autotest to run some simple automated tests:

6991 autotest

When you are finished working on this exercise, you must submit your work by running give:

6991 give-crate

The recommended due date for this exercise is Week 2 Wednesday 21:00:00.

You must run give before Week 10 Friday 17:00:00 to obtain the marks for this exercise. Note that this is an individual exercise; the work you submit with give must be entirely your own.

Exercise:
Dealing with IO

In this exercise we will be translating a simple C program into rust.

#include <stdio.h>
#include <stdlib.h>
#include <string.h>

#define MAX_NAME_LEN 100

int main(void) {
	printf("What is your name? ");

	// allocate some absurd amount of memory
	char name[100];
	fgets(name, MAX_NAME_LEN, stdin);

	// trim the newline
	name[strcspn(name, "\n")] = 0;

	// if name is empty, print a message and exit
	if (name[0] == '\0') {
		printf("No name entered :(, goodbye.\n");
		return 1;
	} else {
		printf("Hello, %s, nice to meet you!\n", name);
	}
}

This program should ask for a name, accept it on the same line and then if a name is present, output the name!

If no name is present (when the user hits "enter" on their keyboard) , it should output another message: "No name entered :(, goodbye.".

The program should behave the same, regardless of running in C or Rust

6991 cargo run
Hello! What is your name: Shrey
Hello, Shrey! Nice to meet you :)

6991 cargo run
Hello! What is your name: 
You didn't enter a name!

Hint 1

The C code uses the function strscpn to remove the newline character from the end of the string.

We need to find documentation for a Rust equivalent to this function, where could we look?

Hint 2

The standard library Rust documentation is available at https://docs.rs/std

We can search for the function we need using the search bar at the top of the page.

E.g. search for "trim" - and the first link should be the trim function.

When you think your program is working, you can use autotest to run some simple automated tests:

6991 autotest

When you are finished working on this exercise, you must submit your work by running give:

6991 give-crate

The recommended due date for this exercise is Week 2 Wednesday 21:00:00.

You must run give before Week 10 Friday 17:00:00 to obtain the marks for this exercise. Note that this is an individual exercise; the work you submit with give must be entirely your own.

Submission

When you are finished each exercise make sure you submit your work by running give.

You can run give multiple times.

Don't submit any exercises you haven't attempted.

If you are working at home, you may find it more convenient to upload your work via give's web interface.

The recommended due date for this week's exercises is Week 2 Wednesday 21:00:00.

You cannot obtain marks by e-mailing your code to tutors or lecturers.

Automarking will be run continuously throughout the term, using test cases different to those autotest runs for you. (Hint: do your own testing as well as running autotest.)

After automarking is run you can view your results here or by running this command on a CSE machine:

6991 classrun -sturec