C linked list

exvor · 04-25-2006, 04:32 PM

Hey im trying my luck at creating a linked list and im not sure if the program ive written is actually doing this. I find feedback a good learning expiance but being that im teaching myself and no one around me knows programming im asking here. I hope no one minds

here is the code

Code:

#include<stdio.h>
#include<stdlib.h>
	   struct listnode
							{
	   	           char data;
	   	           struct listnode *nextptr;
	   	                      };

int main()
{



	   	char dat;
	   	typedef struct listnode LISTNODE;
	   	typedef LISTNODE *LISTNODEPTR;
	   	int choice = 1;
        char datenter[10];

	   	LISTNODEPTR newptr;
	   	LISTNODEPTR current = NULL;

	   	do {
	   		   printf("enter 1 to add a list item 2 to quit\n");
	   		   printf(":>");

	   		   scanf("%s",datenter);
	   		   sscanf(datenter,"%d",&choice);

	   		  fflush(stdin);
	   		 if (choice == 1)
	   		 {
	   		 	    newptr = malloc (sizeof(LISTNODE));
	   		 	    if (newptr == NULL)
	   		 	         {
	   		 	         	 printf("Not enough memory to allocate\n");
	   		 	         	 return 1;
	   		 	          }
	   		 	    printf("Please enter a charecter to add to the list\n");
	   		 	    printf(":>");
	   		 	      scanf("%s",datenter);
	   		   sscanf(datenter,"%c",&dat);

	   		 	    fflush(stdin);

	   		 	    newptr->data = dat;
	   		 	    newptr->nextptr = current;
	   		 	    current = newptr;
	   		 }
	   		 }while(choice != 2);

    do
    {
    	    if ( current != NULL)
    	        {
    	        	printf("%c",current->data);
    	            current = current->nextptr;
    	        }
           if (current == NULL)
               printf("\nEnd of list\n");
    }while(current != NULL);




	   return 0;


	}

dmail · 04-25-2006, 05:21 PM

whats at

Code:

  
&(listnode->data)+1

after

Code:

scanf("%s",datenter);
   sscanf(datenter,"%c",&dat);

do you see what I'm getting at?
seeing as your working buffer is char datenter[10] why not make list.node = char [10] or malloc the space and use a pointer.

and the following can be done in one go

Code:

typedef struct listnode LISTNODE;
	   	typedef LISTNODE *LISTNODEPTR;

Code:

typedef struct listnode
{
    char[10] data;
    struct listnode *nextptr;
}LISTNODE, *LISTNODEPTR;

Code:

newptr->nextptr = current;
current = newptr;

the above is correct, but i just prefer (it just seems clearer)

Code:

newptr->nextptr = 0;//just a good idea
current->nextptr = newptr;
current = newptr;

exvor · 04-27-2006, 05:52 PM

Because i dont want the structures to hold the entire string but rather just a charecter enterd. I m only doing it this way to allvate the \n that is left in the stdin. I tried just suing getc and fflush on stdin but that wasent working. So i did it this way by taking all the char entered by the user up to 10 and then parsing though the input to get the char i wanted.

Vagrant · 04-27-2006, 06:10 PM

Well, this isn't really a linked list, but its on its way. In order for this to be a linked list, a usable one anyway, you need to maintain "head" pointer (pointer to the first node). Also, I probably wouldn't put the struct defintion and typedefs inside main, they should really be outside of main.

exvor · 04-28-2006, 05:25 AM

I posted the finshed code if anyone was intrested. Its more of a stack then a list tho. Im trying a list now but im getting stuck even with that.