CODEWITHSUNDEEP
c
JonnyMca1081
JonnyMca1081

Reputation: 49

c- Error Conlficting types within linked list struct

"I'm trying to implement a Linked List that will later make uses of a lexicographical sort function, but I keep getting an error concerning conflicting types in listnode.

I don't know what the cause of this issue is. Previously I had issues trying to malloc using sizeof and I found that the solution was declaring next as listnode* pointer. It solved that issue, but it still has conflicting types. When I try to compile I get this error message:

ls.c:18:3: error: conflicting types for 'listnode'
} listnode:
ls.c:12:14: note previous declaration of 'listnode' was here
typedef node listnode;

My code:

#include <stdio.h>
#include <stdlib.h>
#include <sys/types.h>
#include <dirent.h>
int strcmp(const char *str1, const char *str2);

//This chunk of code is dedicated to the formation and functions of Linked list
//which will be used to store and sort file names.
typedef struct node node;
typedef node listnode;
#define EMPTY NULL;

typedef struct listnode{
  struct listnode* next;
  char* string;
} listnode;

struct listnode* head;

//This function will print the entire list
void printlist(listnode* head){
 struct listnode* current = head;

 while(current != NULL){
    printf("%s \n", current->string);
    current = current->next;
 }
}

//This function creates a new node
listnode* newNode(char* str, listnode* node){
  listnode* new = (listnode*)malloc(sizeof(listnode*));
  if(new == NULL){
    printf("Error creating new listnode.\n");
    exit(0);
  }
  new->string = str;
  new->next = node;

  return new;
}

//This function will append a new node onto the list
listnode* list_append(listnode* head, char* str){
  if (head == NULL){
    listnode* new = newNode(str, head);
    head = new;
    return head;
  }
  else{
    listnode* current = head;
    while(current-> next != NULL){
      current = current->next;
    }

    listnode* new = newNode(str,NULL);
    current -> next = new;
  }
    return head;
}


//This function earses the list freeing up space
void list_free(listnode* head){
  listnode* current;
  listnode* temp;

  if(head != NULL){
    current = head->next;

    if(head !=NULL){
      current = head -> next;
      head ->next = NULL;
      while(current != NULL){
    temp = current -> next;
    free(current);
    current = temp;
      }
    }
  }
  free(head);
}



//This is the end of the linked list code

int main(int argc, char **argv){
  char *current_dir = NULL;
  DIR *direct_ptr = NULL;
  struct dirent *dir_ptr = NULL;
  unsigned int fileNum = 0;
  int c;
  listnode* head = NULL;

  current_dir = getenv("PWD");
  if(NULL == current_dir){
    printf("\n Error: Couldn't grab current directory.\n");
    return -1;
  }

  direct_ptr = opendir((const char*)current_dir);
  if(NULL == direct_ptr){
    printf("\n Error: couldn't open current directory\n");
    return -1;
  }

  if(argc == 1){
    for(fileNum=0; NULL != (dir_ptr = readdir(direct_ptr)); fileNum++){
      if(dir_ptr->d_name[0] != '.'){
        head = list_append(head, dir_ptr->d_name);
      }
    }
  }
  else{
    if(strcmp(argv[1], "-a") || strcmp(argv[1], "[-a]")){
      for(fileNum=0; NULL != (dir_ptr = readdir(direct_ptr)); fileNum++){
        head = list_append(head, dir_ptr->d_name);
      }
    }
    else{
      printf("\n Unrecognized argument in command line.\n");
      return -1;
    }
  }
return 0;
}

Upvotes: 0

Views: 488

Answers (2)

Barmar
Barmar

Reputation: 781878

You have two definitions of listnode:

typedef node listnode;

and

typedef struct listnode{
  struct listnode* next;
  char* string;
} listnode;

The first one is unnecessary, and won't work, because it uses node, which is defined as 

typedef struct node node;

but you never defined struct node anywhere.

Upvotes: 0

dbush
dbush

Reputation: 224437

You do in fact have conflicting definitions for listnode. You first define the type here:

typedef struct node node;
typedef node listnode;

Then define it again here:

typedef struct listnode{
  struct listnode* next;
  char* string;
} listnode;

In one case it's an alias for struct node and in the other it's an alias for struct listnode.

Get rid of the first one as well as typedef struct node node;

Upvotes: 0

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