编译器抱怨“'->' 的类型参数无效”，为什么？

Question

我有这个功能：

void simul(char *new)
{

    segment_table seg = malloc(sizeof(st));
    segcode newcode = malloc(sizeof(sc));
    int clen = 0;
    seg -> segname = new;
    clen = code_length(seg -> segname);
    seg -> code = read_hexcode(seg -> segname, newcode, clen);
    load_image(seg, clen-3);
    if (strstr(new, "paper_boot-strap loader.hexcode") == NULL)
            run(segment_offset(seg));
}

当我尝试编译我的程序时，出现以下错误：

error: ‘st’ undeclared (first use in this function)
error: ‘sc’ undeclared (first use in this function)
error: invalid type argument of ‘->’ (have ‘segment_table’)
error: invalid type argument of ‘->’ (have ‘segment_table’)
error: invalid type argument of ‘->’ (have ‘segment_table’)
error: invalid type argument of ‘->’ (have ‘segment_table’)

• 我做错了什么？

Answer 1

头文件，例如header.h:

// First an include guard (https://en.wikipedia.org/wiki/Include_guard)
#ifndef HEADER_
#define HEADER_

// Define the structures and their type-aliases
typedef struct st { ... } st;
typedef struct sc { ... } sc;

// Declare a couple of other type-aliases
// (Note that I personally recommend against declaring pointer type-aliases)
// (I personally recommend against using type-aliases for simple types
// like the above structures too)
typedef st *segment_table;
typedef sc *segcode;

// Declare a function prototype
void simul(char *new);

#endif  // HEADER_

一个源文件

#include "header.h"

void simul(char *new)
{
    ...
}

第二个源文件

#include "header.h"

int main(void)
{
    sumul("some string");
}