vault backup: 2022-06-09 14:40:26

Affected files:
.obsidian/workspace
02. PARA/03. Resources（資源）/C++17/rvalue.md
02. PARA/03. Resources（資源）/C++17/智慧指標.md

.obsidian/workspace

@@ -10,7 +10,7 @@
         "state": {
           "type": "markdown",
           "state": {
-            "file": "02. PARA/03. Resources（資源）/C++17/rvalue.md",
+            "file": "02. PARA/03. Resources（資源）/C++17/智慧指標.md",
             "mode": "source",
             "source": true
           }
@@ -23,7 +23,7 @@
         "state": {
           "type": "outline",
           "state": {
-            "file": "02. PARA/03. Resources（資源）/C++17/rvalue.md"
+            "file": "02. PARA/03. Resources（資源）/C++17/智慧指標.md"
           }
         }
       }
@@ -81,7 +81,7 @@
             "state": {
               "type": "backlink",
               "state": {
-                "file": "02. PARA/03. Resources（資源）/C++17/rvalue.md",
+                "file": "02. PARA/03. Resources（資源）/C++17/智慧指標.md",
                 "collapseAll": true,
                 "extraContext": true,
                 "sortOrder": "alphabetical",
@@ -125,12 +125,12 @@
   },
   "active": "94f0e8a81af6c9e2",
   "lastOpenFiles": [
+    "02. PARA/03. Resources（資源）/C++17/智慧指標.md",
     "02. PARA/03. Resources（資源）/C++17/rvalue.md",
     "00. TOP/01. TODO.md",
     "02. PARA/03. Resources（資源）/git/submodule.md",
     "02. PARA/03. Resources（資源）/git.md",
     "02. PARA/01. Project（專案）/008. Sentinel.md",
-    "02. PARA/03. Resources（資源）/C++17/智慧指標.md",
     "02. PARA/03. Resources（資源）/C++17/lvalue.md",
     "02. PARA/03. Resources（資源）/FFMPEG/01. Setup.md",
     "02. PARA/03. Resources（資源）/FFMPEG/00. Introduction.md",

02. PARA/03. Resources（資源）/C++17/rvalue.md

@@ -190,7 +190,13 @@ BigBuffer constructor
 BigBuffer copy operator, copy 104857600Bytes
 ```
 
-還是使用 copy operator
+還是使用 copy assignment operator 來複製，理由是一樣的，需要一個明確的 `std::move()` 來表示「轉移」的行動，把程式改成：
+```cpp
+BigBuffer b1, b2;
+b2 = std::move(b1);
+```
+
+這樣就可以了。
 
 ## 參考
 - [Value categories - cppreference.com](https://en.cppreference.com/w/cpp/language/value_category)

02. PARA/03. Resources（資源）/C++17/智慧指標.md

@@ -60,6 +60,15 @@ std::unique_ptr<int> ptr2 = ptr1; // Error
 在Visual Studio 2017上，錯誤訊息是這樣：`error C2280: 'std::unique_ptr<int,std::default_delete<int>>::unique_ptr(const std::unique_ptr<int,std::default_delete<int>> &)': attempting to reference a deleted function`。
 其實就是`unique_ptr`的copy constructor跟assignment operator都被標記為delete了。
 
+### Move a unique_ptr
+如果一定要把 unique_ptr 指定給別人可以嗎？可以的，用 `std::move()` 來轉移：
+```cpp
+auto ptr1 = std::make_unique<int>(5);
+// do something
+auto anotherPtr = std::move(ptr1);
+```
+
+ptr1原本所管理的指標會轉移給 anotherPtr，
 
 ## shared_ptr
 建立一個 `shared_ptr` 是使用[`std::make_shared()`](https://en.cppreference.com/w/cpp/memory/shared_ptr/make_shared)：