Question

我正在一个有4个文件的项目中：main.c list.c hash.c structs.c和相应的.h文件。问题是在list.c中，我需要链接structs.h。这给我一个错误，说structs.c中的函数与structs.h文件中的该函数的声明冲突。

在lists.h中，我执行#include“ structs.h；在lists.c中，我执行#include” lists.h“ 而且我没有任何错误。在stucts.c中，我#include“ structs.h”

lists.h：

#include "structs.h"
#include <stdio.h>
#include <stdlib.h>
#include <string.h>

typedef struct list{
   Instr head;
   struct list *tail;
} *ILIST;

ILIST mkList(Instr, ILIST);

lists.c：

#include "lists.h"
#include <stdlib.h>
#include <stdio.h>
#include <string.h>
#include <ctype.h>

ILIST mkList(Instr n, ILIST l1) {
  ILIST l = malloc(sizeof(struct list));
  l->head = n;
  l->tail = l1;
  return l;
}

structs.h：

#include <stdio.h>
#include <stdlib.h>
#include <string.h>

typedef enum  {START, QUIT, ATRIB, ADD, SUB, MUL, PRINT, READ, IF, GOTO, LABEL} OpKind;
typedef enum {INT_CONST, STRING, EMPTY} ElemKind;

typedef struct{
  ElemKind kind;
  union
  {
    int val;
    char* name;
  }content;
} Elem;

structs.c：

#include "structs.h"
#include <stdlib.h>
#include <stdio.h>
#include <string.h>
#include <ctype.h>

我得到这样的错误

In file included from lists.h:1:0,
                 from main.c:3:
structs.h:5:16: error: redeclaration of enumerator ‘START’
 typedef enum  {START, QUIT, ATRIB, ADD, SUB, MUL, PRINT, READ, IF, GOTO, LABEL} OpKind;
                ^~~~~

In file included from main.c:1:0:
structs.h:5:16: note: previous definition of ‘START’ was here
 typedef enum  {START, QUIT, ATRIB, ADD, SUB, MUL, PRINT, READ, IF, GOTO, LABEL} OpKind;
                ^~~~~

Answer 1

Header Guards

只包括标题防护，例如：


#ifndef __GUARD_STRUCTS__
#define__GUARD_STRUCTS__

#include <stdio.h>
#include <stdlib.h>
#include <string.h>

typedef enum  {START, QUIT, ATRIB, ADD, SUB, MUL, PRINT, READ, IF, GOTO, LABEL} OpKind;
typedef enum {INT_CONST, STRING, EMPTY} ElemKind;

typedef struct{
  ElemKind kind;
  union
  {
    int val;
    char* name;
  }content;
} Elem;

#endif

在C中链接多个头文件

1 个答案: