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Rust 学习笔记：编程练习（一）

Convert temperatures between Fahrenheit and Celsius

华氏度（F）与摄氏度（C）的转换公式为：F = C×1.8 + 32。

经过简单的代数变换可以得到华氏度转摄氏度的公式：C = (F - 32)÷1.8。

fn celsius_to_fahrenheit(celsius: f32) -> f32 {celsius * 1.8 + 32.0
}fn fahrenheit_to_celsius(fahrenheit: f32) -> f32 {(fahrenheit - 32.0) / 1.8
}fn main() {let celsius: f32 = 0.0;println!("{celsius}°C 转换为华氏度是 {}°F",celsius_to_fahrenheit(celsius));let fahrenheit: f32 = 212.0;println!("{fahrenheit}°F 转换为摄氏度是 {}°C",fahrenheit_to_celsius(fahrenheit));
}

运行结果：

Generate the nth Fibonacci number

斐波那契数列从第 3 项开始，每一项都等于前两项之和。

具体来说，设F(n)为该数列的第n项（n∈N*），则递推公式为：F(n) = F(n-1) + F(n-2)（n≥3）‌

‌初始值‌：F(0) = 0，F(1) = 1‌

fn fibonacci(i: i32) -> i32 {if i == 0 {return 0;}if i == 1 {return 1;}fibonacci(i - 1) + fibonacci(i - 2)
}fn main() {for i in 0..=10 {println!("F({}) = {}", i, fibonacci(i));}
}

运行结果：

Print the lyrics to the Christmas carol “The Twelve Days of Christmas,” taking advantage of the repetition in the song

这首歌的歌词，表面上是讲圣诞节的十二天里要做的事，看起来其实就只是一首很可爱的歌而已，好像没有什么太大的含意在里面，其实，不只是这样喔！“圣诞节的十二日”可说是一首寓意极为深远的“启蒙歌曲”。这首圣诞歌最原始是由英国的新教派所写成，由于十六世纪之后的一两百年，英格兰的国会并不承认这个教派，所以他们依法不能传教，或公开从事他们的信仰活动。在当时，身为一位新教徒可是违法的呢！被抓到之后，轻则牢狱之灾，重则被砍头或被吊死都有可能。既然如此，新教派应该如何秘密传教呢？于是，他们便写了这首歌！歌曲乍听之下跟宗教完全不相干，只是在讲十二天里要为圣诞节准备十二种礼物，其实，这十二种礼物暗示着里十二种宗教上的含义。

fn main() {let times = ["first", "second", "third", "fourth", "fifth", "sixth", "seventh", "eighth", "ninth","tenth", "eleventh", "twelfth",];let items = ["a partridge in a pear tree","two turtle doves","three french hens","four calling birds","five gold rings","six geese a-laying","seven swans a-swimming","eight maids a-milking","nine ladies dancing","ten lords a-leaping","eleven pipers piping","twelve drummers drumming",];for i in 0..times.len() {print!("On the {} day of Christmas, ", times[i]);print!("my true love sent to me: ");for j in (0..=i).rev() {if j == 0 {if i != 0 {print!("and ");}println!("{}. ", items[j]);} else {print!("{}, ", items[j]);}}}
}

运行结果：

On the first day of Christmas, my true love sent to me: a partridge in a pear tree. 
On the second day of Christmas, my true love sent to me: two turtle doves, and a partridge in a pear tree. 
On the third day of Christmas, my true love sent to me: three french hens, two turtle doves, and a partridge in a pear tree. 
On the fourth day of Christmas, my true love sent to me: four calling birds, three french hens, two turtle doves, and a partridge in a pear tree. 
On the fifth day of Christmas, my true love sent to me: five gold rings, four calling birds, three french hens, two turtle doves, and a partridge in a pear tree. 
On the sixth day of Christmas, my true love sent to me: six geese a-laying, five gold rings, four calling birds, three french hens, two turtle doves, and a partridge in a pear tree. 
On the seventh day of Christmas, my true love sent to me: seven swans a-swimming, six geese a-laying, five gold rings, four calling birds, three french hens, two turtle doves, and a partridge in a pear tree. 
On the eighth day of Christmas, my true love sent to me: eight maids a-milking, seven swans a-swimming, six geese a-laying, five gold rings, four calling birds, three french hens, two turtle doves, and a partridge in a pear tree. 
On the ninth day of Christmas, my true love sent to me: nine ladies dancing, eight maids a-milking, seven swans a-swimming, six geese a-laying, five gold rings, four calling birds, three french hens, two turtle doves, and a partridge in a pear tree. 
On the tenth day of Christmas, my true love sent to me: ten lords a-leaping, nine ladies dancing, eight maids a-milking, seven swans a-swimming, six geese a-laying, five gold rings, four calling birds, three french hens, two turtle doves, and a partridge in a pear tree. 
On the eleventh day of Christmas, my true love sent to me: eleven pipers piping, ten lords a-leaping, nine ladies dancing, eight maids a-milking, seven swans a-swimming, six geese a-laying, five gold rings, four calling birds, three french hens, two turtle doves, and a partridge in a pear tree. 
On the twelfth day of Christmas, my true love sent to me: twelve drummers drumming, eleven pipers piping, ten lords a-leaping, nine ladies dancing, eight maids a-milking, seven swans a-swimming, six geese a-laying, five gold rings, four calling birds, three french hens, two turtle doves, and a partridge in a pear tree.