init code

4.Variable Bindings/4.2 Scope and Shadowing/Cargo.lock

@@ -0,0 +1,7 @@
+# This file is automatically @generated by Cargo.
+# It is not intended for manual editing.
+version = 3
+
+[[package]]
+name = "scope_and_shadowing"
+version = "0.1.0"

4.Variable Bindings/4.2 Scope and Shadowing/Cargo.toml

@@ -0,0 +1,8 @@
+[package]
+name = "scope_and_shadowing"
+version = "0.1.0"
+edition = "2021"
+
+# See more keys and their definitions at https://doc.rust-lang.org/cargo/reference/manifest.html
+
+[dependencies]

4.Variable Bindings/4.2 Scope and Shadowing/src/main.rs

@@ -0,0 +1,45 @@
+fn example01() {
+    // 在当前函数作用域中 绑定 1 到变量 long_lived_binding
+    let long_lived_binding = 1;
+
+    // 这个是一个内部嵌套的小范围作用域
+    {
+        // 这个变量声明只在当前的小范围内生效
+        let short_lived_binding = 2;
+
+        println!("inner short: {}", short_lived_binding);
+    }
+    // 嵌套的作用域结束，该作用域内的全部变量都会被回收
+
+    // 报错! `short_lived_binding` 这个变量已经被回收了
+    println!("outer short: {}", short_lived_binding);
+    // FIXME ^ 注释这行代码
+
+    println!("outer long: {}", long_lived_binding);
+}
+
+fn example02() {
+    let shadowed_binding = 1;
+
+    {
+        // 这里使用的变量值是外面的函数作用域的值
+        println!("before being shadowed: {}", shadowed_binding);
+
+        // 这里重新定义了一个同名的变量，进行了变量的遮蔽(shadowing)
+        let shadowed_binding = "abc";
+
+        println!("shadowed in inner block: {}", shadowed_binding);
+    }
+    // 小作用域已经结束，这里的变量使用的依旧是函数作用域的值
+    println!("outside inner block: {}", shadowed_binding);
+
+    // 这里对上面定义的变量重新定义，遮蔽（shadowing）了前面的变量声明
+    let shadowed_binding = 2;
+    println!("shadowed in outer block: {}", shadowed_binding);
+}
+
+fn main() {
+    example01();
+    example02();
+    println!("Hello, world!");
+}