init helloworld

data/1.rust初阶/1.预备知识/1.rust简介/config.json

 {
   "node_id": "rust-7c394f164d8f44519521f03db08a1321",
   "keywords": [],
-  "children": [],
-  "export": []
+  "children": [
+    {
+        "Rust的起源": {
+            "keywords": [
+                "Rust的起源",
+                "起源",
+                "Rust"
+            ],
+            "children": []
+        }
+    }
+  ],
+  "export": [
+      "helloworld.json"
+  ]
 }
\ No newline at end of file

data/1.rust初阶/1.预备知识/1.rust简介/helloworld.json

+{
+    "type": "code_options",
+    "author": "幻灰龙",
+    "source": "helloworld.md",
+    "notebook_enable": true
+}
\ No newline at end of file

data/1.rust初阶/1.预备知识/1.rust简介/helloworld.md

+# Hello World
+
+编写一个输出 "Hello,World!" 的 Rust 程序，以下错误的是？
+
+## 答案
+
+```rust
+fn main() {
+    let str1 = "Hello,";
+    let str2 = "World!";
+    println!("{}", str1+str2);
+}
+```
+
+## 选项
+
+### 直接打印
+
+```rust
+fn main() {
+    let str = "Hello,World!";
+    println!("{}", str);
+}
+```
+
+### 使用格式划宏拼接
+
+```rust
+fn main() {
+    let str = "Hello";
+    let str = format!("{},World", str);
+    println!("{}", str);
+}
+```
+
+### 使用 String::from
+
+```rust
+fn main() {
+    let str1 = String::from("Hello");
+    let str2 = String::from("World");
+    let str = format!("{},{}!", str1, str2);
+    println!("{}", str);
+}
+
+```
+
+### 使用mut+push_str
+
+```rust
+fn main() {
+    let mut str1 = String::from("Hello,");
+    let str2 = String::from("World!");
+    str1.push_str(str2.as_str());
+    println!("{}", str1);
+}
+```
\ No newline at end of file