reference, constant in-class initializer

https://github.com/huihut/interview/issues/79

README.md

@@ -69,7 +69,7 @@
     * 自身是常量的指针（常量指针，const pointer）
 * 引用
     * 指向常量的引用（reference to const）
-    * 没有 const reference，因为引用本身就是 const pointer
+    * 没有 const reference，因为引用只是对象的别名，引用不是对象，不能用 const 修饰
 
 > （为了方便记忆可以想成）被 const 修饰（在 const 后面）的值不可改变，如下文使用例子中的 `p2`、`p3`
 
@@ -82,7 +82,7 @@ const 使用
 class A
 {
 private:
-    const int a;                // 常对象成员，只能在初始化列表赋值
+    const int a;                // 常对象成员，可以使用初始化列表或者类内初始化
 
 public:
     // 构造函数

README_en.md

@@ -71,9 +71,9 @@ English
 * Pointer
      * Pointer to const
      * A pointer to a constant itself (const pointer)
-* Quote
+* Reference
      * Reference to const
-     * There is no const reference because the reference itself is a const pointer
+     * There is no const reference because the reference is an alias of an object, the reference is not an object
 
 > (Think of it for convenience) The value modified by const (after const) cannot be changed, such as `p2`, `p3` in the usage example below
 
@@ -87,7 +87,7 @@ const use
 class A
 {
 private:
-    const int a;                // constant object member, can only be assigned in the initialization list
+    const int a;                // constant object member, can use initialization list or in-class initializer
 
 public:
     // Constructor

docs/README.md

@@ -62,7 +62,7 @@
     * 自身是常量的指针（常量指针，const pointer）
 * 引用
     * 指向常量的引用（reference to const）
-    * 没有 const reference，因为引用本身就是 const pointer
+    * 没有 const reference，因为引用只是对象的别名，引用不是对象，不能用 const 修饰
 
 > （为了方便记忆可以想成）被 const 修饰（在 const 后面）的值不可改变，如下文使用例子中的 `p2`、`p3`
 
@@ -75,7 +75,7 @@ const 使用
 class A
 {
 private:
-    const int a;                // 常对象成员，只能在初始化列表赋值
+    const int a;                // 常对象成员，可以使用初始化列表或者类内初始化
 
 public:
     // 构造函数

docs/en.md

@@ -64,9 +64,9 @@
 * Pointer
      * Pointer to const
      * A pointer to a constant itself (const pointer)
-* Quote
+* Reference
      * Reference to const
-     * There is no const reference because the reference itself is a const pointer
+     * There is no const reference because the reference is an alias of an object, the reference is not an object
 
 > (Think of it for convenience) The value modified by const (after const) cannot be changed, such as `p2`, `p3` in the usage example below
 
@@ -80,7 +80,7 @@ const use
 class A
 {
 private:
-    const int a;                // constant object member, can only be assigned in the initialization list
+    const int a;                // constant object member, can use initialization list or in-class initializer
 
 public:
     // Constructor
@@ -95,7 +95,7 @@ public:
 void function()
 {
     // object
-    A b;                        // ordinary object, can call all member functions, update constant member variables
+    A b;                        // ordinary object, can call all member functions
     const A a;                  // constant object, can only call constant member functions
     const A *p = &a;            // pointer variable, point to a constant object
     const A &q = a;             // reference to constant object