此聲明沒有存儲類或類型說明符

編譯器報錯提示 此聲明沒有存儲類或類型說明符 或 xx does not name a type

個人原因

因為我在頭文件中運行了如下語句

struct EXAMPLE examples;
examples.input = "hello world"

但是 函數外只能定義全局變量或者對象 ，而不能執行語句及調用函數 。

可以改為

struct EXAMPLE examples = {.input = "hello world"};   

但是注意C語言中結構體初始化時，對於內部元素的順序沒有要求，但是C++不一樣。
因為C++結構體初始化時，必須按照定義的順序進行初始化，不能夠跳過其中內容而初始化其他選項，或者定義的順序先后有問題。
否則會報錯:sorry, unimplemented: non-trivial designated initializers not supported

c++最好這么寫

struct EXAMPLE examples = {"hello world"};   

原因2

i just had this problem, and like Arckaroph have said : the problem is that when we include
a header file in a source code file, and we use in it the directive #ifndef, we can't include
it again in a header file to give a type of it's included class to a variable in source code file

example :

class1.h contains Class1 class2.h contains Class2 class2 have a private variable V with
class1 type if we include class1.h in class2.CPP we can't include it in class2.h to give V a class1 type.

so we put in class2.cpp class2.h before class1.h or we delete class1.h from class2.cpp