error: declaration of anonymous struct must be a definition|
时间: 2024-02-03 21:03:24 浏览: 120
这个错误通常是由于在结构体中声明了一个匿名结构体,但是没有给出具体的定义。在 C 语言中,匿名结构体只能用在定义时,而不能用在声明中。
例如,以下代码会产生这个错误:
```c
struct my_struct {
struct {
int a;
int b;
};
};
```
正确的写法应该是给匿名结构体命名或者在定义时给出具体的定义:
```c
struct my_substruct {
int a;
int b;
};
struct my_struct {
struct my_substruct sub;
};
```
或者
```c
struct my_struct {
struct {
int a;
int b;
} sub;
};
```
这样就可以避免这个错误了。
相关问题
declaration of anonymous union must be a definition
Yes, a declaration of an anonymous union must also be a definition. In C language, an anonymous union is a union that does not have a tag name associated with it. It can only be declared and defined at the same time, without a separate declaration and definition. Here's an example:
```c
#include <stdio.h>
int main() {
union {
int x;
float y;
} u; // Anonymous union declaration and definition
u.x = 10;
printf("Value of x: %d\n", u.x);
u.y = 3.14;
printf("Value of y: %.2f\n", u.y);
return 0;
}
```
In the above code, the anonymous union `u` is declared and defined within the `main` function. It contains two members, `x` and `y`, which can be accessed interchangeably.
D:\Qtku\sqlite\05\5_2\mainwindow.cpp:41: error: out-of-line declaration of a member must be a definition
这个错误是由于在D:\Qtku\sqlite\05\5_2\mainwindow.cpp文件的第41行出现了一个成员的声明,但没有提供定义导致的。在C++中,如果在类的定义中声明了一个成员函数,那么必须在类外部提供该成员函数的定义。
要解决这个错误,你需要在类外部提供该成员函数的定义。你可以在mainwindow.cpp文件中找到该成员函数的声明,并确保在该文件中提供了该成员函数的定义。
如果你需要更具体的帮助,请提供相关代码片段,我将尽力帮助你解决问题。