🚀 go-pugleaf

titan@pegasus.odyssee.net (Molle Anthony) wrote:

>Hi it's me again, the new guy to "C".

>Here's a data structures problem. Can someone tell me why the code
>below does not work.   Please be kind -- I get enough abuse from my
>wife hahahaha!!

Please compare with your original code.

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

typedef struct letter_tag
{
   char element;
   struct letter_tag *next;
} LETTER_TYPE;

/* is actually a list_ptr */
LETTER_TYPE *stack1_ptr=NULL;

/* is actually a list_add() */
void push(char letr);


main()
{
   char letter_retrieved;
   /* I added the following variables */
   /* It's not really a requirement they be single letter names... */
   /* I'd use `c' though, instead of `letter_retrieved' */
   LETTER_TYPE *t;
   int i;

   printf("You are supposed to type something in now...\n");

   do
   {
      /* you should never store the result of getchar()
         in a `char': type ^Z (MS-DOS, right?) to see why... */
      letter_retrieved = getchar();
      push(letter_retrieved);
   } while (letter_retrieved != '\n');

   /* test it */
   printf("\n");
   for(i=0, t=stack1_ptr; t ; t=t->next, i++)
	printf("element %d is `%c'\n", i, t->element);
   printf("end of elements: anything beyond here is plutonium...\n");

   /* aha: void main() in diguise! 
      I'd recommend "return 0;" */
   return;
}


void push(char letr)
{
   LETTER_TYPE *temp_ptr;
   temp_ptr=(LETTER_TYPE*)malloc(sizeof(LETTER_TYPE));
   if (temp_ptr==NULL)
   {
      printf("Not Enough Ram.\nErm, I mean: \"Out of swapspace\"\n");
      return;
   }

   temp_ptr->element = letr;

   /* "next" will actually point to the previous element */
   /* This is the easiest way, but elements are stored in
      reverse order... */
   /* Real "next" pointers followable from a "list_head"
      are left as an exercise for the reader... */
   temp_ptr->next = stack1_ptr;
   stack1_ptr = temp_ptr;

   return;
}


==
Miguel Carrasquer Vidal                     ~ ~
Amsterdam                   _____________  ~ ~
mcv@pi.net                 |_____________|||

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