c - 警告:不兼容的指针类型从“mode_t”(又称为“unsigned int *”)分配给“node_t *”(也称为“结构节点*”)

我们的项目是使用我们学院一位教授开发的机器人和软件制作电影。该库称为MyroC，机器人将这个库用于许多功能。理想情况下，我们让机器人拍摄用户输入的许多帧（图片）。用户还可以选择将“场景”或少量子电影插入主电影。

我是学习C语言的初学者。在我最近的学校项目中，我和我的搭档在使用C语言中的指针和链接列表时遇到了很多麻烦。我们了解为列表中的节点分配值和更改地址的基本思想，但是我们不能似乎弄清楚了我们的警告来自何处。我们搜索了各种在线资源和文本以比较我们的代码语法，但看不到哪里可能做错任何事情。

这是我们的代码：

//This part is contained in a separate header file called "movie.h"

    struct node { /* Singly-linked list nodes contain a Picture and point to next */
      Picture frame;
      node_t * next;
    };

    typedef struct node node_t;   /* Shorthand type for nodes in the picture list */

    typedef struct {     /* Wrapper struct for the movie as a linked list */
      node_t * first;
      node_t * last;
    } movie_t;

// This part is contained in a separate file called "movie.c"
// An appropriate reference is made to movie.h
// #include "movie.h"

    movie_t
    create (void)
    {
      movie_t movie = {NULL, NULL}; // initially create an empty movie
      return movie;
    } // movie

    size_t
    size (movie_t * movie)
    {
      unsigned int count = 0;
      node_t * current = movie->first;
      while (current != NULL) {
        count++;
        current = current->next;
      }
        return count;
    } // size

    bool
    is_empty (movie_t * movie)
    {
      if (size(movie)==0) // movie contains no frames
        return true;
      else
        return false; // movie contains frames
    } // empty


    bool
    add (movie_t * movie, Picture frame) // add a frame to the end of the movie
    {
      int before_size = size(movie);

      node_t * new_node;
      new_node = malloc(sizeof(node_t));

      if (new_node == NULL) {
        printf("Error, malloc failed.\n");
        exit(EXIT_FAILURE);
      }

      node_t * cursor = movie->first;
      while(cursor->next != NULL) {
        cursor=cursor->next;
      }
      cursor->next = new_node;
      movie->last = new_node;
      new_node->frame = frame;

      if (before_size < size(movie) && (is_empty(movie)==false))
        return true;
      else
        return false;
    } // add


    void // insert a frame before index
    insert (movie_t * movie, movie_t * scene, unsigned int index)
    {
      node_t *insertion;
      insertion = malloc(sizeof(node_t));
      if (insertion == NULL) {
        printf("Error, malloc failed.\n");
        exit(EXIT_FAILURE);
      }

      insertion = movie->first;

      for (unsigned int i = 0; i < index; i++) {
        if (insertion != NULL)
          insertion = insertion->next;
      }
      scene->last = insertion->next;
      insertion->next = scene->first;

    } // insert

终端输出

error: unknown type name 'node_t'; did you mean 'mode_t'?
node_t * next;
^~~~~~
mode_t
/usr/include/x86_64-linux-gnu/sys/types.h:70:18: note: 'mode_t' declared here

最佳答案

您的第一个错误消息揭示了所有内容。在声明它之前，您正在使用node_t，该操作在它下面进行。

在使用之前，需要声明/定义事物。

那就走吧

typedef struct node node_t;   /* Shorthand type for nodes in the picture list */

变成...

typedef struct node node_t;   /* Shorthand type for nodes in the picture list */

//This part is contained in the header file "movie.h"
struct node { /* Singly-linked list nodes contain a Picture and point to next */
   Picture frame;
    node_t * next;
};

关于c - 警告:不兼容的指针类型从“mode_t”(又称为“unsigned int *”)分配给“node_t *”(也称为“结构节点*”)，我们在Stack Overflow上找到一个类似的问题：https://stackoverflow.com/questions/55886843/