CODEWITHSUNDEEP
clinked-listscanf
user10703426
user10703426

Reputation:

fscanf return value and linked list

This is part of my code.

while(1)
    {
      struct client* newnode = malloc(sizeof(client));

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

      if(head->next == NULL)
      {
       newnode->next = head->next;
       head->next=newnode;
      }


     ReadEOF = fscanf(fp1,"%d %s %s %s %s\n",&(newnode->ID),newnode->PW,newnode->NAME,newnode->ADDRESS,newnode->PNUM);

     if((ReadEOF)!= 5)
     {
       break;
     }

     ++NumofClient;
     printf("%d",NumofClient);

   }   //make newnodes

These codes are written before loop.

 struct client* head=malloc(sizeof(client));
 head->next = NULL;
 int NumofClient = 0;
 int ReadEOF;

This is struct client.

typedef struct client{
  int ID;
  char PW[100],NAME[100],ADDRESS[100],PNUM[100];
  struct client* next;
}client;

This is client.txt file.

 123 aa aa aa aa aa
 234 bb bb bb bb bb
 567 cc cc cc cc cc

I expected the value of NumofClient as 3.

but I found program goes out from the loop when the value of NumofClient is 1.

It means fscanf funtion`s return value was not 5 at 2nd attempt.

Or, are there any error occurred during the linked list implementation?

If you need , I will gladly write the full code in comment

Upvotes: 1

Views: 68

Answers (1)

David Ranieri
David Ranieri

Reputation: 41036

You are overwritting (memory leak) and assigning garbage (non initialized value) to the new node in:

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

I think you want

  newnode->next = head;
  head = newnode;

Upvotes: 1

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