C ++结构-错误1错误C2143：语法错误：缺少';' 在“ *”之前

Question

when i try to compile the following, i receive the error "Error 1 error C2143: syntax error : missing ';' before '*'". Does anyone know why am i receiving this error? What am i doing wrong here?

struct HE_edge {
HE_vert* vert; // vertex at the end of the half-edge<br>
HE_edge* pair; // oppositely oriented half-edge<br>
HE_face* face; // the incident face<br>
HE_edge* prev; // previous half-edge around the face<br>
HE_edge* next; // next half-edge around the face<br>
};

struct HE_vert {
float x, y, z; // the vertex coordinates<br>
HE_edge* edge; // one of the half-edges emanating from the vertex<br>
};

struct HE_face {
HE_edge* edge; // one of the half-edges bordering the face<br>
};

Answer 1

Try to declare your structs in the right order : Since HE_edge depends on HE_vert and HE_face, declare them before.

struct HE_vert;
struct HE_face;

struct HE_edge {
HE_vert* vert; // vertex at the end of the half-edge<br>
HE_edge* pair; // oppositely oriented half-edge<br>
HE_face* face; // the incident face<br>
HE_edge* prev; // previous half-edge around the face<br>
HE_edge* next; // next half-edge around the face<br>
};

struct HE_vert {
float x, y, z; // the vertex coordinates<br>
HE_edge* edge; // one of the half-edges emanating from the vertex<br>
};

struct HE_face {
HE_edge* edge; // one of the half-edges bordering the face<br>
};

Answer 2

You need to forward declare HE_vert and HE_face before you use them in HE_edge .

// fwd declarations. Can use "struct" or "class" interchangeably.
struct HE_vert;
struct HE_face;

struct HE_edge { /* as before */ };

See When to use forward declaration?

Answer 3

You need to declare all the classes before you use their types to make pointers:

struct HE_edge;
struct HE_vert;
struct HE_face;

// your code

Answer 4

You must declare identifiers before you use them. For structures this is simply done by eg

struct HE_vert;

Place that before the definition of HE_edge .

Answer 5

The first declaration has no idea what HE_vert and HE_face is, to you need to tell the compiler what are those:

struct HE_face;
struct HE_vert;//tell compiler what are HE_vert and HE_face

struct HE_edge {
HE_vert* vert; // vertex at the end of the half-edge<br>
HE_edge* pair; // oppositely oriented half-edge<br>
HE_face* face; // the incident face<br>
HE_edge* prev; // previous half-edge around the face<br>
HE_edge* next; // next half-edge around the face<br>
};

struct HE_vert {
float x, y, z; // the vertex coordinates<br>
HE_edge* edge; // one of the half-edges emanating from the vertex<br>
};

struct HE_face {
HE_edge* edge; // one of the half-edges bordering the face<br>
};

Razvan.