how to delete the repeated word

[icable]

i have no idea to delete the repeated word and sort the string. Can anyone help me?
i get the word from infile and generate the outfile which delete the repeated word.
for example
infile
i
am
i
a
boy

outfile
a
am
boy
i

my code is below. what's wrong? Thx everyone helps me

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

struct llist                      
{
                    
   char word[20];                
   struct llist *next;            
};
typedef struct llist node;      
typedef node *llink;

void main()
{
   
    FILE *infile1 = fopen("wordlist.txt","r");
	FILE *outfile1 = fopen("wordlist1.txt","w");
	
	llink head;                    
    llink ptr;
     
	int i=0,count=0;
   
    head = ( llink ) malloc(sizeof(node)); 
   head->next = NULL;            
   ptr = head;     
   while(!feof(infile1))  
   {
       
       fscanf(infile1,"%s",ptr->word);     
       ptr->next = ( llink ) malloc(sizeof(node));
       ptr->next->next = NULL;   
       ptr = ptr->next;
	   count++;
   }
  
   ptr = head;                   
   while(i<count-1)
   {
     fprintf(outfile1,"%s\n",ptr->word);
     ptr = ptr->next; 
	 i++;
   }
   
  fclose(infile1);
  fclose(outfile1);
 
 
 
}

[Brighteyes]

You really should be using a binary search tree for this, that way you could sort the words and restrict duplicates very very very easily. As it is you'll have to linear search the list for every new word and see if it's already there. If it is then don't insert it.