在C中传递链表时如何解决这些冲突的类型错误？

Question

我对C还是很陌生，对链表没有太多的经验。我正在尝试在FCFS中创建磁盘调度程序，并将跟踪请求添加到分配的队列（链接列表）中，并且在尝试编译时收到大量警告和错误，但我不知道为什么。我得到的错误在第86和101行：'AddToList'和'RemoveFromList'的类型冲突。如果有人可以帮助我弄清楚问题所在以及如何解决，将不胜感激。谢谢！

#include <stdio.h>
#include <math.h>
#include <stdlib.h>
#include <values.h>
#include <time.h>
#include <stdbool.h>

/* function declarations */
int trackReqs(void);
int numTrack(void);
void AddToList(struct Queue_Struct *req_queue, int trackNum);
int RemoveFromList(struct Queue_Struct *req_queue);

// global variable declarations/initializations
unsigned seed;
int fileReqs;
bool first = true;

struct Queue_Node{
  int trackNumber;
  struct Queue_Node *next;
};

struct Queue_Struct{
  struct Queue_Node *q_head;
  struct Queue_Node *q_tail;
};

struct Queue_Struct fcfs;

void main(){
  fcfs.q_head = NULL;
  fcfs.q_tail = NULL;
  printf("Seed for the random number generator: ");
  scanf("%d", &seed);
  srand(seed);
  //printf("\n");
  printf("Number of file requests: ");
  scanf("%d", &fileReqs);
  //printf("\n");

  // local variable declarations/initializations
  int totalReqs = 0;
  int numFileReqs = 0;
  float totalHeadMove = 0;
  int currTrack = 0;
  float diff;
  float average;

  do { // do this...
    int numTrackReqs = trackReqs(); // call function to get a random number between 1 and 5 to represent the number of track requests for the current file request
    for (int i = 0; i < numTrackReqs; i++) { // for each track request for the current file request...
      int trackNum = numTrack(); // call function to get a random number between 0 and 799 to represent the number of the track requested
      AddToList(&fcfs, trackNum); // call function to add the track request to the queue
      first = false;
    }
    int nextTrack = RemoveFromList(&fcfs); // call function to remove the next (first) track request from the queue (signifying that the disk head will be moved to that track) and have that track returned
    diff = abs((float)nextTrack - (float)currTrack); // calculate the head movement for the current file request
    totalHeadMove += diff; // add the head movement for the current file request to the total head movement
    totalReqs++; // increase number of total requests by 1
    currTrack = nextTrack; // make the current track now the next track
    numFileReqs++; // increase number of file requests by 1
  } while(numFileReqs <= fileReqs); // ...for each file request
  average = totalHeadMove / (float) numFileReqs; // calculate the average total head movement for each file request and print the result
  printf("Average head movement: %5.2f\n", average);
}

int trackReqs(void){
  int rand_num = (rand() % (5 - 1 + 1)) + 1; // generate random number from 1 to 5 representing number of track requests for the current file request
  return rand_num;
}

int numTrack(void){
  int rand_num = rand() % 800; // generate random number from 0 to 799 representing
  return rand_num;
}

void AddToList(struct Queue_Struct *req_queue, int trackNum){
  struct Queue_Node *newnode;
  newnode = (struct Queue_Node *) malloc(sizeof(struct Queue_Node));
  newnode->next = NULL;
  newnode->trackNumber = trackNum;
  if(req_queue->q_tail == NULL){
    req_queue->q_head = newnode;
    req_queue->q_tail = newnode;
    return;
  }
  req_queue->q_tail->next = newnode;
  req_queue->q_tail = newnode;
  return;
}

int RemoveFromList(struct Queue_Struct *req_queue){
  struct Queue_Node *loc;
  int first_req;
  if(req_queue->q_head == NULL){
    printf("***Error - Queue is Empty***\n");
    return(NULL);
  }
  loc = req_queue->q_head;
  first_req = loc->trackNumber;
  if(req_queue->q_head == req_queue->q_tail){
    req_queue->q_tail = NULL;
    req_queue->q_head = NULL;
    return first_req;
  }
  req_queue->q_head = loc->next;
  free(loc);
  return first_req;
}

Answer 1

发表评论作为答案：问题在于涉及结构类型的相关函数的前向声明之前已定义了这些类型。

我不记得确切的规则，有时您确实需要在定义结构类型之前先提及它，但这不是其中一种。