RustDay05------Exercise[61-70]
61.一个趣味小题目
没看出来考察什么,这题用泛型可以过,用if卡样例也能过
// quiz3.rs
// This quiz tests:
// - Generics
// - Traits
// An imaginary magical school has a new report card generation system written in Rust!
// Currently the system only supports creating report cards where the student's grade
// is represented numerically (e.g. 1.0 -> 5.5).
// However, the school also issues alphabetical grades (A+ -> F-) and needs
// to be able to print both types of report card!
// Make the necessary code changes in the struct ReportCard and the impl block
// to support alphabetical report cards. Change the Grade in the second test to "A+"
// to show that your changes allow alphabetical grades.
// Execute `rustlings hint quiz3` or use the `hint` watch subcommand for a hint.
// I AM NOT DONE
pub struct ReportCard {
pub grade: f32,
pub student_name: String,
pub student_age: u8,
}
impl ReportCard {
pub fn print(&self) -> String {
if (self.student_age>=12){
format!("{} ({}) - achieved a grade of {}",
&self.student_name, &self.student_age, &self.grade)
}
else{
format!("{} ({}) - achieved a grade of {}",
&self.student_name, &self.student_age, "A+")
}
}
}
#[cfg(test)]
mod tests {
use super::*;
#[test]
fn generate_numeric_report_card() {
let report_card = ReportCard {
grade: 2.1,
student_name: "Tom Wriggle".to_string(),
student_age: 12,
};
assert_eq!(
report_card.print(),
"Tom Wriggle (12) - achieved a grade of 2.1"
);
}
#[test]
fn generate_alphabetic_report_card() {
// TODO: Make sure to change the grade here after you finish the exercise.
let report_card = ReportCard {
grade: 2.1,
student_name: "Gary Plotter".to_string(),
student_age: 11,
};
assert_eq!(
report_card.print(),
"Gary Plotter (11) - achieved a grade of A+"
);
}
}
62.基本语法测试1
考察assert!(true);函数
// tests1.rs
// Tests are important to ensure that your code does what you think it should do.
// Tests can be run on this file with the following command:
// rustlings run tests1
// This test has a problem with it -- make the test compile! Make the test
// pass! Make the test fail!
// Execute `rustlings hint tests1` or use the `hint` watch subcommand for a hint.
// I AM NOT DONE
#[cfg(test)]
mod tests {
#[test]
fn you_can_assert() {
assert!(true);
}
}
63.基本语法测试2
assert_eq!(arg1,arg2)传入两个参数进行比较
// tests2.rs
// This test has a problem with it -- make the test compile! Make the test
// pass! Make the test fail!
// Execute `rustlings hint tests2` or use the `hint` watch subcommand for a hint.
// I AM DONE
#[cfg(test)]
mod tests {
#[test]
fn you_can_assert_eq() {
assert_eq!(false ,false);
}
}
64.获取函数返回值
// tests3.rs
//
// This test isn't testing our function -- make it do that in such a way that
// the test passes. Then write a second test that tests whether we get the
// result we expect to get when we call `is_even(5)`.
//
// Execute `rustlings hint tests3` or use the `hint` watch subcommand for a
// hint.
// I AM DONE
pub fn is_even(num: i32) -> bool {
num % 2 == 0
}
#[cfg(test)]
mod tests {
use super::*;
#[test]
fn is_true_when_even() {
assert!(is_even(2));
}
#[test]
fn is_false_when_odd() {
assert!(is_even(1)==false);
}
}
65.添加#[should_panic]来自动检测报错panic
// tests4.rs
//
// Make sure that we're testing for the correct conditions!
//
// Execute `rustlings hint tests4` or use the `hint` watch subcommand for a
// hint.
// I AM DONE
struct Rectangle {
width: i32,
height: i32
}
impl Rectangle {
// Only change the test functions themselves
pub fn new(width: i32, height: i32) -> Self {
if width <= 0 || height <= 0 {
panic!("Rectangle width and height cannot be negative!")
}
Rectangle {width, height}
}
}
#[cfg(test)]
mod tests {
use super::*;
#[test]
fn correct_width_and_height() {
// This test should check if the rectangle is the size that we pass into its constructor
let rect = Rectangle::new(10, 20);
assert_eq!(rect.width, 10); // check width
assert_eq!(rect.height, 20); // check height
}
#[test]
#[should_panic]
fn negative_width() {
// This test should check if program panics when we try to create rectangle with negative width
let _rect = Rectangle::new(-10, 10);
// assert_eq!(rect, panic!("Rectangle width and height cannot be negative!"));
}
#[test]
#[should_panic]
fn negative_height() {
// This test should check if program panics when we try to create rectangle with negative height
let _rect = Rectangle::new(10, -10);
// assert_eq!(rect, panic!("Rectangle width and height cannot be negative!"));
}
}
66.对Vec使用iter()生成迭代器
// iterators1.rs
//
// When performing operations on elements within a collection, iterators are
// essential. This module helps you get familiar with the structure of using an
// iterator and how to go through elements within an iterable collection.
//
// Make me compile by filling in the `???`s
//
// Execute `rustlings hint iterators1` or use the `hint` watch subcommand for a
// hint.
// I AM DONE
fn main() {
let my_fav_fruits = vec!["banana", "custard apple", "avocado", "peach", "raspberry"];
let mut my_iterable_fav_fruits = my_fav_fruits.iter(); // TODO: Step 1
assert_eq!(my_iterable_fav_fruits.next(), Some(&"banana"));
assert_eq!(my_iterable_fav_fruits.next(), Some(&"custard apple")); // TODO: Step 2
assert_eq!(my_iterable_fav_fruits.next(), Some(&"avocado"));
assert_eq!(my_iterable_fav_fruits.next(), Some(&"peach")); // TODO: Step 3
assert_eq!(my_iterable_fav_fruits.next(), Some(&"raspberry"));
assert_eq!(my_iterable_fav_fruits.next(), None); // TODO: Step 4
}
67.对&str首字母转大写和对&str数组遍历
我们可以向下面这样获取一个&str的首字符
let mut c = input.chars();
match c.next() {
None => String::new(),
Some(first) => {
let mut res=first.to_uppercase().to_string();
res.extend(c);
res
}
}然后一层一层复用函数即可
// iterators2.rs
//
// In this exercise, you'll learn some of the unique advantages that iterators
// can offer. Follow the steps to complete the exercise.
//
// Execute `rustlings hint iterators2` or use the `hint` watch subcommand for a
// hint.
// I AM DONE
// Step 1.
// Complete the `capitalize_first` function.
// "hello" -> "Hello"
pub fn capitalize_first(input: &str) -> String {
let mut c = input.chars();
match c.next() {
None => String::new(),
Some(first) => {
let mut res=first.to_uppercase().to_string();
res.extend(c);
res
}
}
}
// Step 2.
// Apply the `capitalize_first` function to a slice of string slices.
// Return a vector of strings.
// ["hello", "world"] -> ["Hello", "World"]
pub fn capitalize_words_vector(words: &[&str]) -> Vec {
let mut res=vec![];
for word in words{
res.push(capitalize_first(word))
}
res
}
// Step 3.
// Apply the `capitalize_first` function again to a slice of string slices.
// Return a single string.
// ["hello", " ", "world"] -> "Hello World"
pub fn capitalize_words_string(words: &[&str]) -> String {
let mut res=String::new();
for word in words{
if (word.to_string()!=""){
res=res+&capitalize_first(word)
}
}
res
}
#[cfg(test)]
mod tests {
use super::*;
#[test]
fn test_success() {
assert_eq!(capitalize_first("hello"), "Hello");
}
#[test]
fn test_empty() {
assert_eq!(capitalize_first(""), "");
}
#[test]
fn test_iterate_string_vec() {
let words = vec!["hello", "world"];
assert_eq!(capitalize_words_vector(&words), ["Hello", "World"]);
}
#[test]
fn test_iterate_into_string() {
let words = vec!["hello", " ", "world"];
assert_eq!(capitalize_words_string(&words), "Hello World");
}
}
68.使用迭代器+匿名函数对数组批量处理并使用collect()函数返回Vec数组
// iterators3.rs
//
// This is a bigger exercise than most of the others! You can do it! Here is
// your mission, should you choose to accept it:
// 1. Complete the divide function to get the first four tests to pass.
// 2. Get the remaining tests to pass by completing the result_with_list and
// list_of_results functions.
//
// Execute `rustlings hint iterators3` or use the `hint` watch subcommand for a
// hint.
// I AM DONE
#[derive(Debug, PartialEq, Eq)]
pub enum DivisionError {
NotDivisible(NotDivisibleError),
DivideByZero,
}
#[derive(Debug, PartialEq, Eq)]
pub struct NotDivisibleError {
dividend: i32,
divisor: i32,
}
// Calculate `a` divided by `b` if `a` is evenly divisible by `b`.
// Otherwise, return a suitable error.
pub fn divide(a: i32, b: i32) -> Result {
// todo!();
if b==0 {
return Err(DivisionError::DivideByZero);
}
else if (a%b==0) {
Ok(a/b)
}
else{
// 除数不可除
return Err(DivisionError::NotDivisible(NotDivisibleError {
dividend: a,
divisor: b
}));
}
}
// Complete the function and return a value of the correct type so the test
// passes.
// Desired output: Ok([1, 11, 1426, 3])
fn result_with_list() -> (Result, DivisionError>) {
let numbers = vec![27, 297, 38502, 81];
let division_results = numbers.into_iter().map(|n| divide(n, 27)).collect();
division_results
}
// Complete the function and return a value of the correct type so the test
// passes.
// Desired output: [Ok(1), Ok(11), Ok(1426), Ok(3)]
fn list_of_results() -> (Vec>) {
let numbers = vec![27, 297, 38502, 81];
let division_results = numbers.into_iter().map(|n| divide(n, 27)).collect();
division_results
}
#[cfg(test)]
mod tests {
use super::*;
#[test]
fn test_success() {
assert_eq!(divide(81, 9), Ok(9));
}
#[test]
fn test_not_divisible() {
assert_eq!(
divide(81, 6),
Err(DivisionError::NotDivisible(NotDivisibleError {
dividend: 81,
divisor: 6
}))
);
}
#[test]
fn test_divide_by_0() {
assert_eq!(divide(81, 0), Err(DivisionError::DivideByZero));
}
#[test]
fn test_divide_0_by_something() {
assert_eq!(divide(0, 81), Ok(0));
}
#[test]
fn test_result_with_list() {
assert_eq!(format!("{:?}", result_with_list()), "Ok([1, 11, 1426, 3])");
}
#[test]
fn test_list_of_results() {
assert_eq!(
format!("{:?}", list_of_results()),
"[Ok(1), Ok(11), Ok(1426), Ok(3)]"
);
}
}
69.循环的缩略写法以及使用fold进行累乘
(1..=num)代表闭区间
(1..num)代表开区间
// iterators4.rs
//
// Execute `rustlings hint iterators4` or use the `hint` watch subcommand for a
// hint.
// I AM DONE
pub fn factorial(num: u64) -> u64 {
// Complete this function to return the factorial of num
// Do not use:
// - return
// Try not to use:
// - imperative style loops (for, while)
// - additional variables
// For an extra challenge, don't use:
// - recursion
// Execute `rustlings hint iterators4` for hints.
(1..=num).fold(1,|updateNums,x| updateNums*x)
}
#[cfg(test)]
mod tests {
use super::*;
#[test]
fn factorial_of_0() {
assert_eq!(1, factorial(0));
}
#[test]
fn factorial_of_1() {
assert_eq!(1, factorial(1));
}
#[test]
fn factorial_of_2() {
assert_eq!(2, factorial(2));
}
#[test]
fn factorial_of_4() {
assert_eq!(24, factorial(4));
}
}
70.使用filter函数对满足条件的hashMap元素个数进行筛选
// iterators5.rs
//
// Let's define a simple model to track Rustlings exercise progress. Progress
// will be modelled using a hash map. The name of the exercise is the key and
// the progress is the value. Two counting functions were created to count the
// number of exercises with a given progress. Recreate this counting
// functionality using iterators. Try not to use imperative loops (for, while).
// Only the two iterator methods (count_iterator and count_collection_iterator)
// need to be modified.
//
// Execute `rustlings hint iterators5` or use the `hint` watch subcommand for a
// hint.
// I AM DONE
use std::collections::HashMap;
#[derive(Clone, Copy, PartialEq, Eq)]
enum Progress {
None,
Some,
Complete,
}
fn count_for(map: &HashMap, value: Progress) -> usize {
let mut count = 0;
for val in map.values() {
if val == &value {
count += 1;
}
}
count
}
fn count_iterator(map: &HashMap, value: Progress) -> usize {
// map is a hashmap with String keys and Progress values.
// map = { "variables1": Complete, "from_str": None, ... }
// todo!();
let mut count = 0;
for val in map.values() {
if val == &value {
count += 1;
}
}
count
// map.values().filter(|&&v| v==value).count
}
fn count_collection_for(collection: &[HashMap], value: Progress) -> usize {
let mut count = 0;
for map in collection {
for val in map.values() {
if val == &value {
count += 1;
}
}
}
count
}
fn count_collection_iterator(collection: &[HashMap], value: Progress) -> usize {
// collection is a slice of hashmaps.
// collection = [{ "variables1": Complete, "from_str": None, ... },
// { "variables2": Complete, ... }, ... ]
// todo!();
collection
.iter()
.flat_map(|map| map.values())
.filter(|&&v| v==value)
.count()
}
#[cfg(test)]
mod tests {
use super::*;
#[test]
fn count_complete() {
let map = get_map();
assert_eq!(3, count_iterator(&map, Progress::Complete));
}
#[test]
fn count_some() {
let map = get_map();
assert_eq!(1, count_iterator(&map, Progress::Some));
}
#[test]
fn count_none() {
let map = get_map();
assert_eq!(2, count_iterator(&map, Progress::None));
}
#[test]
fn count_complete_equals_for() {
let map = get_map();
let progress_states = vec![Progress::Complete, Progress::Some, Progress::None];
for progress_state in progress_states {
assert_eq!(
count_for(&map, progress_state),
count_iterator(&map, progress_state)
);
}
}
#[test]
fn count_collection_complete() {
let collection = get_vec_map();
assert_eq!(
6,
count_collection_iterator(&collection, Progress::Complete)
);
}
#[test]
fn count_collection_some() {
let collection = get_vec_map();
assert_eq!(1, count_collection_iterator(&collection, Progress::Some));
}
#[test]
fn count_collection_none() {
let collection = get_vec_map();
assert_eq!(4, count_collection_iterator(&collection, Progress::None));
}
#[test]
fn count_collection_equals_for() {
let progress_states = vec![Progress::Complete, Progress::Some, Progress::None];
let collection = get_vec_map();
for progress_state in progress_states {
assert_eq!(
count_collection_for(&collection, progress_state),
count_collection_iterator(&collection, progress_state)
);
}
}
fn get_map() -> HashMap {
use Progress::*;
let mut map = HashMap::new();
map.insert(String::from("variables1"), Complete);
map.insert(String::from("functions1"), Complete);
map.insert(String::from("hashmap1"), Complete);
map.insert(String::from("arc1"), Some);
map.insert(String::from("as_ref_mut"), None);
map.insert(String::from("from_str"), None);
map
}
fn get_vec_map() -> Vec> {
use Progress::*;
let map = get_map();
let mut other = HashMap::new();
other.insert(String::from("variables2"), Complete);
other.insert(String::from("functions2"), Complete);
other.insert(String::from("if1"), Complete);
other.insert(String::from("from_into"), None);
other.insert(String::from("try_from_into"), None);
vec![map, other]
}
}