Refining Ch03.

projects/tuple_demo/src/main.rs

@@ -1,5 +1,22 @@
-fn main() {
-    let a: [i32; 5] = [-1, 0, 1, 2, 3];
+use std::io;
 
-    println! ("a[0]: {a.0}");
+fn main() {
+    let a = [1, 2, 3, 4, 5];
+
+    println! ("请输入一个数组索引。");
+
+    let mut index = String::new();
+
+    io::stdin()
+        .read_line(&mut index)
+        .expect("读取行失败，failed to read line");
+
+    let index: usize = index
+        .trim()
+        .parse()
+        .expect("输入的所以并非一个数字");
+
+    let element = a[index];
+
+    println! ("位于索引 {index} 出的元素值为：{element}");
 }