I can't get out of my while loop!!

This is a discussion on I can't get out of my while loop!! within the C Programming forums, part of the General Programming Boards category; OK, I wrote this program to try and learn about linked lists, basically if you run it, it asks you ...

  1. #1
    Registered User
    Join Date
    Sep 2005
    Posts
    84

    I can't get out of my while loop!!

    OK, I wrote this program to try and learn about linked lists, basically if you run it, it asks you to input a name, and after you hit enter, it asks you to type 1 if you want to input another name or 0 if you don't.

    If you put in a few names then hit 0 it should return the list of names you put in. But it doesnt. It works fine if you only input 1 name then hit 0 after that, but for more than one name it gets stuck.

    It's stuck in the while( response ) portion of my code... but to me the while loop looks fine, if you input 0 it should exit the loop, but it doesn't... Can anyone tell why it doesn't exit? thank you

    Code:
    #include <stdio.h>
    #include <stdlib.h>
    
    /* declare a self-referential structure */
    
    typedef struct elephant {
            char  name[1];
            struct elephant* next;
            }ELEPHANT;
            
    void    print_elephants( const ELEPHANT* ptr );
    ELEPHANT* get_elephants(void);
    
    main()
    {
          ELEPHANT* start;
          start = get_elephants();
          print_elephants( start );
          getchar();
          getchar();
          return EXIT_SUCCESS;
              }
    
    /* get_elephants allocates run-time storage for nodes.  It builds
       the linked list and stores user-supplied names in the name 
       members of the nodes. It returns a pointer to the first such
       node. */
       
    ELEPHANT* get_elephants(void)
    {
              ELEPHANT *current, *first;
              int response;
              
              /* allocate first node */
              current = first = malloc( sizeof ( ELEPHANT ) );
              
              /* store name of first elephant */
              printf( "\n\n\tNAME:\t" );
              scanf( "%s", current -> name );
              
              /* prompt use about another elephant */
              printf( "\n\n\n\tAdd another? (1 == yes, 0 == no)\t" );     
              scanf( "%d", &response );
              
              
              /* Add elephants to list until user signals halt. */
              while ( response ) {
                    /* try to allocate another elephant node */
              if ( ( current -> next = 
                   malloc( sizeof ( ELEPHANT ) ) ) == NULL ) {
                   printf( "Out os memory\nCan't add more elephants\n");
                   return first;
                   }
                   
                   current = current -> next;
                   
                   /* store name of next elephant */
                   printf( "\n\n\tNAME:\t" );
                   scanf( "%s", current -> name );
                   
                   /* prompt user about another elephant */
                   printf( "\n\n\n\tAdd another? ( 1 == yes, 0 == no)\t" );
                   scanf( "d", &response );
                   }
                   
                   /* set link in last node to NULL */
                   current -> next = NULL;
                   return first;
                   
                   }
                   
               
                   
                   /* print_elephants steps through the linked list pointed to by
                   ptr and prints the member names in each node as well as the
                   position of teh node in the list */
                   
                   
              void print_elephants( const ELEPHANT* ptr )
              {
                   int count = 1;
                   printf( "\n\n\n" );
                   while ( ptr != NULL ) {
                         printf( " \nElephant number %d is %s.", 
                         count++, ptr -> name );
                         ptr = ptr -> next;
                         }
                         }
    i've tried while ( response == 1 ) .... it still gets stuck

  2. #2
    Registered User
    Join Date
    Dec 2003
    Posts
    12
    Quote Originally Posted by panfilero

    Code:
                   /* prompt user about another elephant */
                   printf( "\n\n\n\tAdd another? ( 1 == yes, 0 == no)\t" );
                   scanf( "d", &response );
    change the

    Code:
     scanf( "d", &response );
    to
    Code:
     scanf( "%d", &response );

  3. #3
    Registered User
    Join Date
    Sep 2005
    Posts
    84
    God Bless you.

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