Structured Linked List
I had to do this assignment right? Okay, all I supposedly had to do was copy it right out of the book and then change like two things. So then why doesn't it work when I copy it verbatim from the book? Here is the code.
/*
This is the structured linked list program that was asked for week 5 that are due in 2 weeks.
It operates and maintains a list. */
#include
#include
/* self-referential structure */
struct listNode {
char data; /*each ListNode contains a character */
struct listNode *nextPtr; /* pointer to nest node */
}; /* end structure listNode */
//***struct Node{ int data;/ this can be any type data Node *next; Node *prev; }***//
typedef struct listNode ListNode; /* synonmy for struct listNode */
typedef ListNode *ListNodePtr; /* synonmy for listNode */
/* prototypes */
void insert( ListNodePtr *sPtr, char value );
char myDelete( ListNodePtr *sPtr, char value );
int isEmpty( ListNodePtr *sPtr );
void printList( ListNodePtr currentPtr );
void instructions( void );
int main( void )
{
ListNodePtr startPtr = NULL; /* initially there are no nodes */
int choice; /* user's choice */
char item; /* char entered by user */
instructions(); /* display the menu */
printf( "? " );
scanf( "%d", &choice );
/* loop while user does not choose 3 */
while( choice != 3 )
{
switch( choice )
{
case 1:
printf( "Enter a character: " );
scanf( "\n%c", &item );
insert( &startPtr, item ); /* insert item in list */
printList( startPtr );
break;
case 2: /* myDelete an element */
/* if list is not empty */
if ( !isEmpty( startPtr ) )
{
printf( "Enter character to be myDeleted: " );
scanf( "\n%c", &item );
/* if character is found, remove it */
if ( myDelete ( &startPtr, item ) ); /* remove it */
{
printf( "%c myDeleted. \n", item );
printList( startPtr );
} /* end if */
else
{
printf( "%c not found. \n\n ", item );
} /* end else */
} /* end if */
else
{
printf( "List is empty.\n\n" );
} /*end else */
break;
default:
printf( "Invalid choice.\n\n" );
instructions();
break;
} /* end switch */
printf( "? " );
scanf( "%d", &choice );
} /* end while */
printf( "End of run.\n" );
system("PAUSE");
return 0; /* indicates successful termination */
} /* end main */
/* display program instructions to user */
void instructions( void )
{
printf( "Enter your choice:\n"
" 1 to insert an element into the list.\n"
" 2 to myDelete an element from the list.\n"
" 3 to end.\n" );
} /* end function instructions */
/* Insert a new value into the list in sorted order */
void insert( ListNodePtr *sPtr, char value );
{
ListNodePtr newPtr; /* pointer to new node */
ListNodePtr previousPtr; /* pointer to previous node in list */
ListNodePtr currentPtr; /* pointer to current node in list */
newPtr = malloc( sizeof( ListNode ) ); /* create node */
if ( newPtr != NULL ) /* is space available */
{
newPtr->data = value; /* place value in node */
newPtr->nextPtr = NULL; /* node does not link to another node */
previousPtr = NULL;
currentPtr = *sPtr;
/* loop to find the correct location in the list */
while( currentPtr != NULL && value > currentPtr->data )
{
previousPtr = currentPtr; /* walk to... */
currentPtr = currentPtr->nextPtr; /* ...next node */
} /* end while */
/* insert new node at beginning of list */
if ( previousPtr == NULL )
{
newPtr->nextPtr = *sPtr;
*sPtr = newPtr;
} /* end if */
else /* insert new node between previousPtr and currentPtr */
{
previousPtr->nextPtr = newPtr;
newPtr->nextPtr = currentPtr;
} /* end else */
} /* end if */
else
{
printf( "%c not inserted. No memory available.\n", value );
} /* end else */
} /* end function insert */
/* myDelete a list element */
char myDelete( ListNodePtr *sPtr, char value )
{
ListNodePtr previousPtr; /* pointer to previous node in list */
ListNodePtr currentPtr; /* pointer to current node in list */
ListNodePtr tempPtr; /* temporary node pointer */
/* myDelete first node */
if ( value == ( *sPtr )->data )
{
tempPtr = *sPtr; /* hold onto node being removed */
*sPtr = ( *sPtr )->nextPtr; /* de-thread the node */
free (tempPtr ); /* free the de-threaded node */
return value;
} /* end if */
else
{
previousPtr = *sPtr;
currentPtr = (*sPtr )->nextPtr;
/* loop to find the correct location in the list */
while( currentPtr != NULL && currentPtr->data != value )
{
previousPtr = currentPtr; /* walk to... */
currentPtr = currentPtr->nextPtr; /* ...next node */
} /* end while */
/* myDelete node at currentPtr */
if ( currentPtr != NULL )
{
tempPtr = currentPtr;
previousPtr = currentPtr;
previousPtr->nextPtr = currentPtr->nextPtr;
free (tempPtr );
return value;
} /* end if */
} /* end else */
return '\0';
} /* end function myDelete */
/* Return 1 if the list is empty, 0 otherwise */
int isEmpty ( ListNodePtr sPtr )
{
return sPtr == NULL;
} /* end function isEmpty */
/* Print the list */
void printList ( ListNodePtr currentPtr )
{
/* if list is empty */
if ( currentPtr == NULL )
{
printf( "List is empty.\n\n" );
} /* end if */
else
{
printf( "The list is:\n" );
/* while not the end of the list */
while( currentPtr != NULL )
{
printf( "%c --> ", currentPtr->data );
currentPtr = currentPtr->nextPtr;
} /* end while */
printf( "NULL\n\n" );
} /* end else */
}/* end function function printList */