Rust by Example中文

2.2 Tuples

元组(tuple)是一组不同类型的集合。元组由圆括号和具有类型签名值组成， (T1, T2, ...), 其中 T1, T2 是它成员的类型.函数可以用元组返回多个值，因为元组可以持有任意数量的值。

// 元组能被用来作为函数参数以及返回值 fn reverse(pair: (i32, bool)) -> (bool, i32) { // `let` 可以用来把元组成员绑定到变量上 let (integer, boolean) = pair; (boolean, integer) } // The following struct is for the activity. #[derive(Debug)] struct Matrix(f32, f32, f32, f32); fn main() { // 包含一堆不同类型的元组 let long_tuple = (1u8, 2u16, 3u32, 4u64, -1i8, -2i16, -3i32, -4i64, 0.1f32, 0.2f64, 'a', true); // 使用元组索引可以从元组中提取出相应的值 println!("long tuple first value: {}", long_tuple.0); println!("long tuple second value: {}", long_tuple.1); // 元组也可以作为元组的成员 let tuple_of_tuples = ((1u8, 2u16, 2u32), (4u64, -1i8), -2i16); // 元组是可打印的 println!("tuple of tuples: {:?}", tuple_of_tuples); let pair = (1, true); println!("pair is {:?}", pair); println!("the reversed pair is {:?}", reverse(pair)); // 要创建单个元素的元组，必须加逗号`,` // from a literal surrounded by parentheses println!("one element tuple: {:?}", (5u32,)); println!("just an integer: {:?}", (5u32)); //元组可以由解构的方式去创建绑定 let tuple = (1, "hello", 4.5, true); let (a, b, c, d) = tuple; println!("{:?}, {:?}, {:?}, {:?}", a, b, c, d); let matrix = Matrix(1.1, 1.2, 2.1, 2.2); println!("{:?}", matrix) }

Activity

  1. Recap: Add the fmt::Display trait to the Matrix struct in the above example, so that if you switch from printing the debug format {:?} to the display format {}, you see the following output:
    ( 1.1 1.2 )
( 2.1 2.2 )
    You may want to refer back to the example for print display.
  2. Add a transpose function using the reverse function as a template, which accepts a matrix as an argument, and returns a matrix in which two elements have been swapped. For example:
    println!("Matrix:\n{}", matrix)
println!("Transpose:\n{}", transpose(matrix))
    results in the output:
    Matrix:
( 1.1 1.2 )
( 2.1 2.2 )
Transpose:
( 1.1 2.1 )
( 1.2 2.2 )