智能感知：類型的成員 「爲const char * const的[]」 不能有一流初始化

Question

考慮：

class Note 
{ 
public: 
    // ... 
private: 
    static const char* const NOTE_NAMES[12] = 
      { "C", "C#", "D", "D#", "E", "F", "F#", "G", "G#", "A", "A#", "B" }; 
} 

雖然它編譯罰款， 智能感知給了我一個錯誤：

IntelliSense: a member of type "const char *const [12]" cannot have an in-class initializer

這是一個錯誤還是我做錯了什麼？

Answer 1

按照C++標準

If a non-volatile const static data member is of integral or enumeration type, its declaration in the class definition can specify a brace-or-equal-initializer in which every initializer-clause that is an assignmentexpression is a constant expression

所以，你的代碼不符合C++標準。

在另一方面

A static data member of literal type can be declared in the class definition with the constexpr specifier; if so, its declaration shall specify a brace-or-equal-initializer in which every initializer-clause that is an assignment-expression is a constant expression

因此，要獲得你應該寫

static constexpr char* const NOTE_NAMES[12] = 
     { "C", "C#", "D", "D#", "E", "F", "F#", "G", "G#", "A", "A#", "B" };