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My progress 15th challenge
This commit is contained in:
parent
f24861957a
commit
98ef272777
@ -1,4 +1,4 @@
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fn main() {
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// TODO: Fix the code to print "Hello world!".
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printline!("Hello world!");
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println!("Hello world!");
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}
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@ -1,7 +1,7 @@
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# Variables
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In Rust, variables are immutable by default.
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When a variable is immutable, once a value is bound to a name, you can't change that value.
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When a variable is immutable, once a value is bound to a name, you can’t change that value.
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You can make them mutable by adding `mut` in front of the variable name.
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## Further information
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@ -1,6 +1,6 @@
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fn main() {
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// TODO: Add the missing keyword.
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x = 5;
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let x = 5;
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println!("x has the value {x}");
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}
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@ -1,6 +1,6 @@
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fn main() {
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// TODO: Change the line below to fix the compiler error.
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let x;
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let x = 5;
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if x == 10 {
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println!("x is ten!");
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@ -1,6 +1,6 @@
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fn main() {
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// TODO: Change the line below to fix the compiler error.
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let x: i32;
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let x: i32=5;
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println!("Number {x}");
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}
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@ -1,6 +1,6 @@
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// TODO: Fix the compiler error.
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fn main() {
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let x = 3;
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let mut x = 3;
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println!("Number {x}");
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x = 5; // Don't change this line
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@ -1,8 +1,8 @@
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fn main() {
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let number = "T-H-R-E-E"; // Don't change this line
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println!("Spell a number: {number}");
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println!("Spell a number: {number}" );
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// TODO: Fix the compiler error by changing the line below without renaming the variable.
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number = 3;
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let number = 5;
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println!("Number plus two is: {}", number + 2);
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}
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@ -1,5 +1,5 @@
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// TODO: Change the line below to fix the compiler error.
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const NUMBER = 3;
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const NUMBER:u8 = 3;
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fn main() {
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println!("Number: {NUMBER}");
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@ -1,5 +1,6 @@
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// TODO: Add some function with the name `call_me` without arguments or a return value.
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fn call_me(){}
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fn main() {
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call_me(); // Don't change this line
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}
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@ -1,5 +1,5 @@
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// TODO: Add the missing type of the argument `num` after the colon `:`.
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fn call_me(num:) {
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fn call_me(num:i32) {
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for i in 0..num {
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println!("Ring! Call number {}", i + 1);
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}
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@ -6,5 +6,5 @@ fn call_me(num: u8) {
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fn main() {
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// TODO: Fix the function call.
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call_me();
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call_me(8);
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}
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@ -8,7 +8,7 @@ fn is_even(num: i64) -> bool {
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}
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// TODO: Fix the function signature.
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fn sale_price(price: i64) -> {
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fn sale_price(price: i64) -> i64{
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if is_even(price) {
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price - 10
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} else {
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@ -1,6 +1,6 @@
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// TODO: Fix the function body without changing the signature.
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fn square(num: i32) -> i32 {
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num * num;
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num * num
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}
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fn main() {
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@ -4,6 +4,12 @@ fn bigger(a: i32, b: i32) -> i32 {
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// Do not use:
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// - another function call
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// - additional variables
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if a > b {
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return a;
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} else if a < b {
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return b;
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}
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a
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}
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fn main() {
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@ -2,8 +2,10 @@
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fn picky_eater(food: &str) -> &str {
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if food == "strawberry" {
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"Yummy!"
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} else {
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1
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} else if food=="potato"{
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"I guess I can eat that."
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}else {
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"No thanks!"
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}
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}
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@ -19,7 +21,7 @@ mod tests {
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#[test]
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fn yummy_food() {
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// This means that calling `picky_eater` with the argument "strawberry" should return "Yummy!".
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// This means that calling `picky_eater` with the argument "food" should return "Yummy!".
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assert_eq!(picky_eater("strawberry"), "Yummy!");
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}
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@ -3,11 +3,11 @@ fn animal_habitat(animal: &str) -> &str {
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let identifier = if animal == "crab" {
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1
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} else if animal == "gopher" {
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2.0
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2
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} else if animal == "snake" {
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3
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} else {
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"Unknown"
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4
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};
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// Don't change the expression below!
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@ -9,6 +9,8 @@ fn main() {
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// TODO: Define a boolean variable with the name `is_evening` before the `if` statement below.
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// The value of the variable should be the negation (opposite) of `is_morning`.
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// let …
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let is_evening=!is_morning;
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if is_evening {
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println!("Good evening!");
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}
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@ -17,7 +17,7 @@ fn main() {
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// Try a letter, try a digit (in single quotes), try a special character, try a character
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// from a different language than your own, try an emoji 😉
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// let your_character = '';
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let your_character = '*';
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if your_character.is_alphabetic() {
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println!("Alphabetical!");
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} else if your_character.is_numeric() {
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@ -1,7 +1,7 @@
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fn main() {
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// TODO: Create an array called `a` with at least 100 elements in it.
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// let a = ???
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let a=[1;101];
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if a.len() >= 100 {
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println!("Wow, that's a big array!");
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} else {
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@ -9,7 +9,7 @@ mod tests {
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let a = [1, 2, 3, 4, 5];
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// TODO: Get a slice called `nice_slice` out of the array `a` so that the test passes.
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// let nice_slice = ???
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let nice_slice = &a[1..4];
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assert_eq!([2, 3, 4], nice_slice);
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}
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@ -3,6 +3,6 @@ fn main() {
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// TODO: Destructure the `cat` tuple in one statement so that the println works.
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// let /* your pattern here */ = cat;
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let (name,age)=cat;
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println!("{name} is {age} years old");
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}
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@ -1,5 +1,6 @@
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fn main() {
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// You can optionally experiment here.
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}
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#[cfg(test)]
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@ -11,7 +12,8 @@ mod tests {
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// TODO: Use a tuple index to access the second element of `numbers`
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// and assign it to a variable called `second`.
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// let second = ???;
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let second = numbers.1;
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assert_eq!(second, 2, "This is not the 2nd number in the tuple!");
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}
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}
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@ -3,7 +3,7 @@ fn array_and_vec() -> ([i32; 4], Vec<i32>) {
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// TODO: Create a vector called `v` which contains the exact same elements as in the array `a`.
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// Use the vector macro.
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// let v = ???;
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let v: Vec<i32> = a.into_iter().collect();
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(a, v)
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}
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@ -1,9 +1,10 @@
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fn vec_loop(input: &[i32]) -> Vec<i32> {
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let mut output = Vec::new();
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let mut output: Vec<i32> = Vec::new();
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for element in input {
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// TODO: Multiply each element in the `input` slice by 2 and push it to
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// the `output` vector.
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output.push(element * 2);
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}
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output
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@ -24,7 +25,7 @@ fn vec_map(input: &[i32]) -> Vec<i32> {
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input
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.iter()
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.map(|element| {
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// ???
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element*2
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})
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.collect()
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}
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@ -1,6 +1,6 @@
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// TODO: Fix the compiler error in this function.
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fn fill_vec(vec: Vec<i32>) -> Vec<i32> {
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let vec = vec;
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let mut vec = vec;
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vec.push(88);
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@ -20,7 +20,7 @@ mod tests {
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fn move_semantics2() {
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let vec0 = vec![22, 44, 66];
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let vec1 = fill_vec(vec0);
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let vec1 = fill_vec(vec0.clone());
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assert_eq!(vec0, [22, 44, 66]);
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assert_eq!(vec1, [22, 44, 66, 88]);
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@ -1,5 +1,5 @@
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// TODO: Fix the compiler error in the function without adding any new line.
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fn fill_vec(vec: Vec<i32>) -> Vec<i32> {
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fn fill_vec(mut vec: Vec<i32>) -> Vec<i32> {
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vec.push(88);
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vec
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@ -10,8 +10,8 @@ mod tests {
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fn move_semantics4() {
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let mut x = Vec::new();
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let y = &mut x;
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let z = &mut x;
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y.push(42);
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let z = &mut x;
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z.push(13);
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assert_eq!(x, [42, 13]);
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}
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@ -4,12 +4,12 @@
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// removing references (the character `&`).
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// Shouldn't take ownership
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fn get_char(data: String) -> char {
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fn get_char(data: &String) -> char {
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data.chars().last().unwrap()
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}
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// Should take ownership
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fn string_uppercase(mut data: &String) {
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fn string_uppercase(mut data: String) {
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data = data.to_uppercase();
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println!("{data}");
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@ -18,7 +18,8 @@ fn string_uppercase(mut data: &String) {
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fn main() {
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let data = "Rust is great!".to_string();
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get_char(data);
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get_char(&data);
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string_uppercase(data);
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string_uppercase(&data);
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}
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@ -1,9 +1,16 @@
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struct ColorRegularStruct {
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// TODO: Add the fields that the test `regular_structs` expects.
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// What types should the fields have? What are the minimum and maximum values for RGB colors?
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red : u8,
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green :u8,
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blue:u8
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}
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struct ColorTupleStruct(/* TODO: Add the fields that the test `tuple_structs` expects */);
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struct ColorTupleStruct(
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u8,
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u8,
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u8
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);
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#[derive(Debug)]
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struct UnitStruct;
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@ -19,7 +26,7 @@ mod tests {
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#[test]
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fn regular_structs() {
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// TODO: Instantiate a regular struct.
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// let green =
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let green = ColorRegularStruct { red: 0, green: 255, blue: 0 };
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assert_eq!(green.red, 0);
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assert_eq!(green.green, 255);
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@ -29,7 +36,7 @@ mod tests {
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#[test]
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fn tuple_structs() {
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// TODO: Instantiate a tuple struct.
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// let green =
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let green = ColorTupleStruct(0,255,0);
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assert_eq!(green.0, 0);
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assert_eq!(green.1, 255);
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@ -39,7 +46,7 @@ mod tests {
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#[test]
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fn unit_structs() {
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// TODO: Instantiate a unit struct.
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// let unit_struct =
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let unit_struct = UnitStruct;
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let message = format!("{unit_struct:?}s are fun!");
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assert_eq!(message, "UnitStructs are fun!");
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@ -21,6 +21,20 @@ fn create_order_template() -> Order {
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}
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}
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impl Order {
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fn create_orders(name:String,year:u32,made_by_phone:bool,made_by_mobile:bool,made_by_email:bool,item_number:u32,count:u32) -> Order {
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Order {
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name,
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year,
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made_by_phone,
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made_by_mobile,
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made_by_email,
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item_number,
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count,
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}
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}
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}
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fn main() {
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// You can optionally experiment here.
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}
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@ -34,7 +48,8 @@ mod tests {
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let order_template = create_order_template();
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// TODO: Create your own order using the update syntax and template above!
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// let your_order =
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let your_order = Order::create_orders("Hacker in Rust".to_string(), order_template.year, order_template.made_by_phone,
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order_template.made_by_mobile, order_template.made_by_email, order_template.item_number, 1);
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assert_eq!(your_order.name, "Hacker in Rust");
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assert_eq!(your_order.year, order_template.year);
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@ -15,7 +15,7 @@ impl Package {
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// learn about error handling later.
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panic!("Can't ship a package with weight below 10 grams");
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}
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Self {
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sender_country,
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recipient_country,
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@ -24,14 +24,17 @@ impl Package {
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}
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// TODO: Add the correct return type to the function signature.
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fn is_international(&self) {
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fn is_international(&self)->bool {
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// TODO: Read the tests that use this method to find out when a package
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// is considered international.
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self.recipient_country != self.sender_country
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}
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// TODO: Add the correct return type to the function signature.
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fn get_fees(&self, cents_per_gram: u32) {
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fn get_fees(&self, cents_per_gram: u32)->u32 {
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// TODO: Calculate the package's fees.
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self.weight_in_grams*cents_per_gram
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}
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}
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@ -1,10 +1,10 @@
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# Enums
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Rust allows you to define types called "enums" which enumerate possible values.
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Enums are a feature in many languages, but their capabilities differ in each language. Rust's enums are most similar to algebraic data types in functional languages, such as F#, OCaml, and Haskell.
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Enums are a feature in many languages, but their capabilities differ in each language. Rust’s enums are most similar to algebraic data types in functional languages, such as F#, OCaml, and Haskell.
|
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Useful in combination with enums is Rust's "pattern matching" facility, which makes it easy to run different code for different values of an enumeration.
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|
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## Further information
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||||
|
||||
- [Enums](https://doc.rust-lang.org/book/ch06-00-enums.html)
|
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- [Pattern syntax](https://doc.rust-lang.org/book/ch19-03-pattern-syntax.html)
|
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- [Pattern syntax](https://doc.rust-lang.org/book/ch18-03-pattern-syntax.html)
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|
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@ -1,6 +1,11 @@
|
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#[derive(Debug)]
|
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enum Message {
|
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// TODO: Define a few types of messages as used below.
|
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Resize
|
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, Move
|
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, Echo
|
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, ChangeColor
|
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, Quit
|
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}
|
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|
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fn main() {
|
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|
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@ -6,7 +6,11 @@ struct Point {
|
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|
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#[derive(Debug)]
|
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enum Message {
|
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// TODO: Define the different variants used below.
|
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Resize { width: u64, height: u64 },
|
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Move(Point),
|
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Echo(String),
|
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ChangeColor(u8, u8, u8),
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Quit,
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}
|
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|
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impl Message {
|
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|
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@ -46,6 +46,13 @@ impl State {
|
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fn process(&mut self, message: Message) {
|
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// TODO: Create a match expression to process the different message
|
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// variants using the methods defined above.
|
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match message {
|
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Message::Resize { width, height } => State::resize(self, width, height),
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Message::Move(point) => State::move_position(self, point),
|
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Message::Echo(s) => State::echo(self, s),
|
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Message::ChangeColor(r, g, b) => State::change_color(self, r, g, b),
|
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Message::Quit => State::quit(self),
|
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}
|
||||
}
|
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}
|
||||
|
||||
|
||||
@ -1,6 +1,6 @@
|
||||
// TODO: Fix the compiler error without changing the function signature.
|
||||
fn current_favorite_color() -> String {
|
||||
"blue"
|
||||
"blue".to_string()
|
||||
}
|
||||
|
||||
fn main() {
|
||||
|
||||
@ -6,7 +6,7 @@ fn is_a_color_word(attempt: &str) -> bool {
|
||||
fn main() {
|
||||
let word = String::from("green"); // Don't change this line.
|
||||
|
||||
if is_a_color_word(word) {
|
||||
if is_a_color_word(word.as_str()) {
|
||||
println!("That is a color word I know!");
|
||||
} else {
|
||||
println!("That is not a color word I know.");
|
||||
|
||||
@ -1,13 +1,16 @@
|
||||
fn trim_me(input: &str) -> &str {
|
||||
// TODO: Remove whitespace from both ends of a string.
|
||||
input.trim()
|
||||
}
|
||||
|
||||
fn compose_me(input: &str) -> String {
|
||||
// TODO: Add " world!" to the string! There are multiple ways to do this.
|
||||
input.to_string() + " world!"
|
||||
}
|
||||
|
||||
fn replace_me(input: &str) -> String {
|
||||
// TODO: Replace "cars" in the string with "balloons".
|
||||
input.replace("cars", "balloons")
|
||||
}
|
||||
|
||||
fn main() {
|
||||
@ -23,7 +26,6 @@ mod tests {
|
||||
assert_eq!(trim_me("Hello! "), "Hello!");
|
||||
assert_eq!(trim_me(" What's up!"), "What's up!");
|
||||
assert_eq!(trim_me(" Hola! "), "Hola!");
|
||||
assert_eq!(trim_me("Hi!"), "Hi!");
|
||||
}
|
||||
|
||||
#[test]
|
||||
|
||||
@ -13,25 +13,25 @@ fn string(arg: String) {
|
||||
// Your task is to replace `placeholder(…)` with either `string_slice(…)`
|
||||
// or `string(…)` depending on what you think each value is.
|
||||
fn main() {
|
||||
placeholder("blue");
|
||||
string_slice("blue");
|
||||
|
||||
placeholder("red".to_string());
|
||||
string("red".to_string());
|
||||
|
||||
placeholder(String::from("hi"));
|
||||
string(String::from("hi"));
|
||||
|
||||
placeholder("rust is fun!".to_owned());
|
||||
string("rust is fun!".to_owned());
|
||||
|
||||
placeholder("nice weather".into());
|
||||
string_slice("nice weather");
|
||||
|
||||
placeholder(format!("Interpolation {}", "Station"));
|
||||
string(format!("Interpolation {}", "Station"));
|
||||
|
||||
// WARNING: This is byte indexing, not character indexing.
|
||||
// Character indexing can be done using `s.chars().nth(INDEX)`.
|
||||
placeholder(&String::from("abc")[0..1]);
|
||||
string_slice(&String::from("abc")[0..1]);
|
||||
|
||||
placeholder(" hello there ".trim());
|
||||
string_slice(" hello there ".trim());
|
||||
|
||||
placeholder("Happy Monday!".replace("Mon", "Tues"));
|
||||
string("Happy Monday!".replace("Mon", "Tues"));
|
||||
|
||||
placeholder("mY sHiFt KeY iS sTiCkY".to_lowercase());
|
||||
string("mY sHiFt KeY iS sTiCkY".to_lowercase());
|
||||
}
|
||||
|
||||
@ -1,12 +1,12 @@
|
||||
// TODO: Fix the compiler error about calling a private function.
|
||||
mod sausage_factory {
|
||||
// Don't let anybody outside of this module see this!
|
||||
fn get_secret_recipe() -> String {
|
||||
fn _get_secret_recipe() -> String {
|
||||
String::from("Ginger")
|
||||
}
|
||||
|
||||
fn make_sausage() {
|
||||
get_secret_recipe();
|
||||
pub fn make_sausage() {
|
||||
_get_secret_recipe();
|
||||
println!("sausage!");
|
||||
}
|
||||
}
|
||||
|
||||
@ -3,8 +3,8 @@
|
||||
|
||||
mod delicious_snacks {
|
||||
// TODO: Add the following two `use` statements after fixing them.
|
||||
// use self::fruits::PEAR as ???;
|
||||
// use self::veggies::CUCUMBER as ???;
|
||||
pub use self::fruits::PEAR as fruit;
|
||||
pub use self::veggies::CUCUMBER as veggie;
|
||||
|
||||
mod fruits {
|
||||
pub const PEAR: &str = "Pear";
|
||||
@ -18,6 +18,8 @@ mod delicious_snacks {
|
||||
}
|
||||
|
||||
fn main() {
|
||||
|
||||
use delicious_snacks;
|
||||
println!(
|
||||
"favorite snacks: {} and {}",
|
||||
delicious_snacks::fruit,
|
||||
|
||||
@ -5,7 +5,9 @@
|
||||
// your scope. Bonus style points if you can do it with one line!
|
||||
// use ???;
|
||||
|
||||
use std::time::{SystemTime, UNIX_EPOCH};
|
||||
fn main() {
|
||||
|
||||
match SystemTime::now().duration_since(UNIX_EPOCH) {
|
||||
Ok(n) => println!("1970-01-01 00:00:00 UTC was {} seconds ago!", n.as_secs()),
|
||||
Err(_) => panic!("SystemTime before UNIX EPOCH!"),
|
||||
|
||||
@ -8,18 +8,26 @@ use std::collections::HashMap;
|
||||
|
||||
fn fruit_basket() -> HashMap<String, u32> {
|
||||
// TODO: Declare the hash map.
|
||||
// let mut basket =
|
||||
let mut basket =HashMap::new();
|
||||
|
||||
// Two bananas are already given for you :)
|
||||
basket.insert(String::from("banana"), 2);
|
||||
basket.insert("banana".to_string(), 2);
|
||||
|
||||
// TODO: Put more fruits in your basket.
|
||||
basket.insert("apples".to_string(), 2);
|
||||
basket.insert("watermelon".to_string(), 2);
|
||||
basket.insert("pinapple".to_string(), 2);
|
||||
basket.insert("papaya".to_string(), 2);
|
||||
|
||||
basket
|
||||
}
|
||||
|
||||
fn main() {
|
||||
// You can optionally experiment here.
|
||||
let a=vec![1,2,3];
|
||||
let b = a.into_iter().sum::<u64>();
|
||||
|
||||
print!("{b}")
|
||||
}
|
||||
|
||||
#[cfg(test)]
|
||||
@ -35,6 +43,6 @@ mod tests {
|
||||
#[test]
|
||||
fn at_least_five_fruits() {
|
||||
let basket = fruit_basket();
|
||||
assert!(basket.values().sum::<u32>() >= 5);
|
||||
assert!(basket.into_values().sum::<u32>() >= 5);
|
||||
}
|
||||
}
|
||||
|
||||
@ -32,6 +32,11 @@ fn fruit_basket(basket: &mut HashMap<Fruit, u32>) {
|
||||
// TODO: Insert new fruits if they are not already present in the
|
||||
// basket. Note that you are not allowed to put any type of fruit that's
|
||||
// already present!
|
||||
match basket.get(&fruit) {
|
||||
Some(_) => {},
|
||||
None => { basket.insert(fruit, 1); },
|
||||
}
|
||||
|
||||
}
|
||||
}
|
||||
|
||||
|
||||
@ -6,10 +6,10 @@
|
||||
// number of goals the team scored, and the total number of goals the team
|
||||
// conceded.
|
||||
|
||||
use std::collections::HashMap;
|
||||
use std::{collections::HashMap};
|
||||
|
||||
// A structure to store the goal details of a team.
|
||||
#[derive(Default)]
|
||||
#[derive(Default,Debug)]
|
||||
struct TeamScores {
|
||||
goals_scored: u8,
|
||||
goals_conceded: u8,
|
||||
@ -31,6 +31,14 @@ fn build_scores_table(results: &str) -> HashMap<&str, TeamScores> {
|
||||
// Keep in mind that goals scored by team 1 will be the number of goals
|
||||
// conceded by team 2. Similarly, goals scored by team 2 will be the
|
||||
// number of goals conceded by team 1.
|
||||
scores.entry(team_1_name)
|
||||
.and_modify(|a|
|
||||
{a.goals_scored+=team_1_score ; a.goals_conceded+=team_2_score}
|
||||
).or_insert(TeamScores { goals_scored: team_1_score, goals_conceded: team_2_score });
|
||||
scores.entry(team_2_name)
|
||||
.and_modify(|a|
|
||||
{a.goals_scored+=team_2_score ; a.goals_conceded+= team_1_score})
|
||||
.or_insert(TeamScores { goals_scored: team_2_score, goals_conceded: team_1_score });
|
||||
}
|
||||
|
||||
scores
|
||||
@ -38,6 +46,19 @@ fn build_scores_table(results: &str) -> HashMap<&str, TeamScores> {
|
||||
|
||||
fn main() {
|
||||
// You can optionally experiment here.
|
||||
|
||||
const RESULTS: &str = "England,France,4,2
|
||||
France,Italy,3,1
|
||||
Poland,Spain,2,0
|
||||
Germany,England,2,1
|
||||
England,Spain,1,0";
|
||||
|
||||
let mut scores = HashMap::<&str, TeamScores>::new();
|
||||
|
||||
scores.entry("test").or_default();
|
||||
scores.entry("test2").and_modify(|a| { a.goals_conceded += 1; });
|
||||
print!("{scores:?}")
|
||||
|
||||
}
|
||||
|
||||
#[cfg(test)]
|
||||
|
||||
@ -1,9 +1,15 @@
|
||||
// This function returns how much ice cream there is left in the fridge.
|
||||
// This function returns how much icecream there is left in the fridge.
|
||||
// If it's before 22:00 (24-hour system), then 5 scoops are left. At 22:00,
|
||||
// someone eats it all, so no ice cream is left (value 0). Return `None` if
|
||||
// someone eats it all, so no icecream is left (value 0). Return `None` if
|
||||
// `hour_of_day` is higher than 23.
|
||||
fn maybe_ice_cream(hour_of_day: u16) -> Option<u16> {
|
||||
fn maybe_icecream(hour_of_day: u16) -> Option<u16> {
|
||||
// TODO: Complete the function body.
|
||||
|
||||
match hour_of_day {
|
||||
0..22 => Some(5),
|
||||
22..24=>Some(0),
|
||||
_=>None,
|
||||
}
|
||||
}
|
||||
|
||||
fn main() {
|
||||
@ -18,19 +24,19 @@ mod tests {
|
||||
fn raw_value() {
|
||||
// TODO: Fix this test. How do you get the value contained in the
|
||||
// Option?
|
||||
let ice_creams = maybe_ice_cream(12);
|
||||
let icecreams = maybe_icecream(12).unwrap();
|
||||
|
||||
assert_eq!(ice_creams, 5); // Don't change this line.
|
||||
assert_eq!(icecreams, 5); // Don't change this line.
|
||||
}
|
||||
|
||||
#[test]
|
||||
fn check_ice_cream() {
|
||||
assert_eq!(maybe_ice_cream(0), Some(5));
|
||||
assert_eq!(maybe_ice_cream(9), Some(5));
|
||||
assert_eq!(maybe_ice_cream(18), Some(5));
|
||||
assert_eq!(maybe_ice_cream(22), Some(0));
|
||||
assert_eq!(maybe_ice_cream(23), Some(0));
|
||||
assert_eq!(maybe_ice_cream(24), None);
|
||||
assert_eq!(maybe_ice_cream(25), None);
|
||||
fn check_icecream() {
|
||||
assert_eq!(maybe_icecream(0), Some(5));
|
||||
assert_eq!(maybe_icecream(9), Some(5));
|
||||
assert_eq!(maybe_icecream(18), Some(5));
|
||||
assert_eq!(maybe_icecream(22), Some(0));
|
||||
assert_eq!(maybe_icecream(23), Some(0));
|
||||
assert_eq!(maybe_icecream(24), None);
|
||||
assert_eq!(maybe_icecream(25), None);
|
||||
}
|
||||
}
|
||||
|
||||
@ -10,7 +10,7 @@ mod tests {
|
||||
let optional_target = Some(target);
|
||||
|
||||
// TODO: Make this an if-let statement whose value is `Some`.
|
||||
word = optional_target {
|
||||
if let Some(word) = optional_target {
|
||||
assert_eq!(word, target);
|
||||
}
|
||||
}
|
||||
@ -29,7 +29,7 @@ mod tests {
|
||||
// TODO: Make this a while-let statement. Remember that `Vec::pop()`
|
||||
// adds another layer of `Option`. You can do nested pattern matching
|
||||
// in if-let and while-let statements.
|
||||
integer = optional_integers.pop() {
|
||||
while let Some(Some(integer)) = optional_integers.pop() {
|
||||
assert_eq!(integer, cursor);
|
||||
cursor -= 1;
|
||||
}
|
||||
|
||||
@ -8,8 +8,8 @@ fn main() {
|
||||
let optional_point = Some(Point { x: 100, y: 200 });
|
||||
|
||||
// TODO: Fix the compiler error by adding something to this match statement.
|
||||
match optional_point {
|
||||
Some(p) => println!("Coordinates are {},{}", p.x, p.y),
|
||||
match &optional_point {
|
||||
Some(p) => println!("Co-ordinates are {},{}", p.x, p.y),
|
||||
_ => panic!("No match!"),
|
||||
}
|
||||
|
||||
|
||||
@ -1,8 +1,8 @@
|
||||
# Error handling
|
||||
|
||||
Most errors aren't serious enough to require the program to stop entirely.
|
||||
Sometimes, when a function fails, it's for a reason that you can easily interpret and respond to.
|
||||
For example, if you try to open a file and that operation fails because the file doesn't exist, you might want to create the file instead of terminating the process.
|
||||
Most errors aren’t serious enough to require the program to stop entirely.
|
||||
Sometimes, when a function fails, it’s for a reason that you can easily interpret and respond to.
|
||||
For example, if you try to open a file and that operation fails because the file doesn’t exist, you might want to create the file instead of terminating the process.
|
||||
|
||||
## Further information
|
||||
|
||||
|
||||
@ -4,12 +4,12 @@
|
||||
// construct to `Option` that can be used to express error conditions. Change
|
||||
// the function signature and body to return `Result<String, String>` instead
|
||||
// of `Option<String>`.
|
||||
fn generate_nametag_text(name: String) -> Option<String> {
|
||||
fn generate_nametag_text(name: String) -> Result<String,String> {
|
||||
if name.is_empty() {
|
||||
// Empty names aren't allowed
|
||||
None
|
||||
Err(format!("Empty names aren't allowed"))
|
||||
} else {
|
||||
Some(format!("Hi! My name is {name}"))
|
||||
Ok(format!("Hi! My name is {name}"))
|
||||
}
|
||||
}
|
||||
|
||||
|
||||
@ -21,7 +21,8 @@ fn total_cost(item_quantity: &str) -> Result<i32, ParseIntError> {
|
||||
let cost_per_item = 5;
|
||||
|
||||
// TODO: Handle the error case as described above.
|
||||
let qty = item_quantity.parse::<i32>();
|
||||
let qty = item_quantity.parse::<i32>()?;
|
||||
|
||||
|
||||
Ok(qty * cost_per_item + processing_fee)
|
||||
}
|
||||
|
||||
@ -15,7 +15,7 @@ fn total_cost(item_quantity: &str) -> Result<i32, ParseIntError> {
|
||||
|
||||
// TODO: Fix the compiler error by changing the signature and body of the
|
||||
// `main` function.
|
||||
fn main() {
|
||||
fn main() -> Result<(), ParseIntError> {
|
||||
let mut tokens = 100;
|
||||
let pretend_user_input = "8";
|
||||
|
||||
@ -28,4 +28,7 @@ fn main() {
|
||||
tokens -= cost;
|
||||
println!("You now have {tokens} tokens.");
|
||||
}
|
||||
|
||||
Ok(())
|
||||
|
||||
}
|
||||
|
||||
@ -9,8 +9,14 @@ struct PositiveNonzeroInteger(u64);
|
||||
|
||||
impl PositiveNonzeroInteger {
|
||||
fn new(value: i64) -> Result<Self, CreationError> {
|
||||
|
||||
// TODO: This function shouldn't always return an `Ok`.
|
||||
Ok(Self(value as u64))
|
||||
|
||||
match value {
|
||||
x if x < 0 => Err(CreationError::Negative),
|
||||
0 => Err(CreationError::Zero),
|
||||
x => Ok(Self(x as u64)),
|
||||
}
|
||||
}
|
||||
}
|
||||
|
||||
|
||||
@ -6,7 +6,7 @@
|
||||
//
|
||||
// In short, this particular use case for boxes is for when you want to own a
|
||||
// value and you care only that it is a type which implements a particular
|
||||
// trait. To do so, the `Box` is declared as of type `Box<dyn Trait>` where
|
||||
// trait. To do so, The `Box` is declared as of type `Box<dyn Trait>` where
|
||||
// `Trait` is the trait the compiler looks for on any value used in that
|
||||
// context. For this exercise, that context is the potential errors which
|
||||
// can be returned in a `Result`.
|
||||
@ -48,7 +48,7 @@ impl PositiveNonzeroInteger {
|
||||
|
||||
// TODO: Add the correct return type `Result<(), Box<dyn ???>>`. What can we
|
||||
// use to describe both errors? Is there a trait which both errors implement?
|
||||
fn main() {
|
||||
fn main() -> Result<(), Box<dyn Error>> {
|
||||
let pretend_user_input = "42";
|
||||
let x: i64 = pretend_user_input.parse()?;
|
||||
println!("output={:?}", PositiveNonzeroInteger::new(x)?);
|
||||
|
||||
@ -25,7 +25,9 @@ impl ParsePosNonzeroError {
|
||||
}
|
||||
|
||||
// TODO: Add another error conversion function here.
|
||||
// fn from_parse_int(???) -> Self { ??? }
|
||||
fn from_parse_int(err:ParseIntError) -> Self {
|
||||
Self::ParseInt(err)
|
||||
}
|
||||
}
|
||||
|
||||
#[derive(PartialEq, Debug)]
|
||||
@ -43,7 +45,7 @@ impl PositiveNonzeroInteger {
|
||||
fn parse(s: &str) -> Result<Self, ParsePosNonzeroError> {
|
||||
// TODO: change this to return an appropriate error instead of panicking
|
||||
// when `parse()` returns an error.
|
||||
let x: i64 = s.parse().unwrap();
|
||||
let x: i64 = s.parse().map_err(ParsePosNonzeroError::from_parse_int)?;
|
||||
Self::new(x).map_err(ParsePosNonzeroError::from_creation)
|
||||
}
|
||||
}
|
||||
|
||||
@ -6,7 +6,7 @@ fn main() {
|
||||
// TODO: Fix the compiler error by annotating the type of the vector
|
||||
// `Vec<T>`. Choose `T` as some integer type that can be created from
|
||||
// `u8` and `i8`.
|
||||
let mut numbers = Vec::new();
|
||||
let mut numbers: Vec<i16> = Vec::new();
|
||||
|
||||
// Don't change the lines below.
|
||||
let n1: u8 = 42;
|
||||
|
||||
@ -1,12 +1,12 @@
|
||||
// This powerful wrapper provides the ability to store a positive integer value.
|
||||
// TODO: Rewrite it using a generic so that it supports wrapping ANY type.
|
||||
struct Wrapper {
|
||||
value: u32,
|
||||
struct Wrapper<T> {
|
||||
value: T,
|
||||
}
|
||||
|
||||
// TODO: Adapt the struct's implementation to be generic over the wrapped value.
|
||||
impl Wrapper {
|
||||
fn new(value: u32) -> Self {
|
||||
impl<T> Wrapper<T> {
|
||||
fn new(value: T) -> Self {
|
||||
Wrapper { value }
|
||||
}
|
||||
}
|
||||
|
||||
@ -10,6 +10,5 @@ of exercises to Rustlings, but is all about learning to write Macros.
|
||||
|
||||
## Further information
|
||||
|
||||
- [The Rust Book - Macros](https://doc.rust-lang.org/book/ch20-05-macros.html)
|
||||
- [Macros](https://doc.rust-lang.org/book/ch19-06-macros.html)
|
||||
- [The Little Book of Rust Macros](https://veykril.github.io/tlborm/)
|
||||
- [Rust by Example - macro_rules!](https://doc.rust-lang.org/rust-by-example/macros.html)
|
||||
|
||||
@ -4,11 +4,9 @@
|
||||
#[rustfmt::skip]
|
||||
#[allow(unused_variables, unused_assignments)]
|
||||
fn main() {
|
||||
let my_option: Option<&str> = None;
|
||||
// Assume that you don't know the value of `my_option`.
|
||||
// In the case of `Some`, we want to print its value.
|
||||
let my_option: Option<()> = None;
|
||||
if my_option.is_none() {
|
||||
println!("{}", my_option.unwrap());
|
||||
println!("{:?}", my_option.unwrap());
|
||||
}
|
||||
|
||||
let my_arr = &[
|
||||
|
||||
@ -16,6 +16,13 @@ fn main() {
|
||||
// You can optionally experiment here.
|
||||
}
|
||||
|
||||
fn calculate_price_of_apples(cant:u32)->u32{
|
||||
if cant>40{
|
||||
return cant;
|
||||
}
|
||||
cant*2
|
||||
}
|
||||
|
||||
// Don't change the tests!
|
||||
#[cfg(test)]
|
||||
mod tests {
|
||||
|
||||
@ -27,7 +27,15 @@ mod my_module {
|
||||
use super::Command;
|
||||
|
||||
// TODO: Complete the function as described above.
|
||||
// pub fn transformer(input: ???) -> ??? { ??? }
|
||||
pub fn transformer(input: Vec<(String, Command)>) -> Vec<String> {
|
||||
input.into_iter().map(|(s, c)| {
|
||||
match c {
|
||||
Command::Uppercase => s.to_uppercase(),
|
||||
Command::Trim => s.trim().to_string(),
|
||||
Command::Append(size) => format!("{}{}", s, "bar".repeat(size)),
|
||||
}
|
||||
}).collect()
|
||||
}
|
||||
}
|
||||
|
||||
fn main() {
|
||||
@ -37,12 +45,12 @@ fn main() {
|
||||
#[cfg(test)]
|
||||
mod tests {
|
||||
// TODO: What do we need to import to have `transformer` in scope?
|
||||
// use ???;
|
||||
use super::my_module::transformer;
|
||||
use super::Command;
|
||||
|
||||
#[test]
|
||||
fn it_works() {
|
||||
let input = vec![
|
||||
let input: Vec<(String, Command)> = vec![
|
||||
("hello".to_string(), Command::Uppercase),
|
||||
(" all roads lead to rome! ".to_string(), Command::Trim),
|
||||
("foo".to_string(), Command::Append(1)),
|
||||
|
||||
Loading…
x
Reference in New Issue
Block a user