This needs to be done in C programming.

Question

Modify the C Program Linked List given below to create a queue. The same functions for adding, removing and printing nodes should be present.

EXTRA: Include print statements to explain what is happening in the queue as the functions are running.

#include <stdio.h>

#include <stdlib.h>

struct listNode {

       char data;

       struct listNode *nextPtr;

typedef struct listNode ListNode;

typedef ListNode *ListNodePtr;

void insert( ListNodePtr *sPtr, char value );

char delete( ListNodePtr *sPtr, char value );

int isEmpty( ListNodePtr sPtr );

void printList( ListNodePtr currentPtr );

void instructions( void );

int main( void )

{

  ListNodePtr startPtr = NULL;

  int choice;

  char item;

   

  instructions();

  printf( "? " );

  scanf( "%d", &choice );

  while ( choice != 3 ) {

    switch ( choice ) {

      case 1:

        printf( "Enter a character: " );

        scanf( "\n%c", &item );

        insert( &startPtr, item );

        printList( startPtr );

        break;

       case 2:

        if ( !isEmpty( startPtr ) ) {

          printf( "Enter character to be deleted: " );

          scanf( "\n%c", &item );

          if ( delete( &startPtr, item ) ) {

            printf( "%c deleted.\n", item );

            printList( startPtr );

          }

          else {

            printf( "%c not found.\n\n", item );

          }

        }

        else {

          printf( "List is empty.\n\n" );

        }

        break;

      default:

         printf( "Invalid choice.\n\n" );

         instructions();

         break;

         }

    printf( "? " );

    scanf( "%d", &choice );

}

  printf( "End of run.\n" );

  return 0;

   }

void instructions( void )

{

  printf( "Enter your choice:\n"

     " 1 to insert an element into the list.\n"

     " 2 to delete an element from the list.\n"

     " 3 to end.\n" );

}

  

void insert( ListNodePtr *sPtr, char value )

{

  ListNodePtr newPtr = malloc( sizeof( ListNode ) );

  if ( newPtr != NULL ) {

    newPtr->data = value;

    newPtr->nextPtr = NULL;

    ListNodePtr previousPtr = NULL; 

    ListNodePtr currentPtr = *sPtr;

    while ( currentPtr != NULL && value > currentPtr->data ) {

      previousPtr = currentPtr;

      currentPtr = currentPtr->nextPtr;

    }

    if ( previousPtr == NULL ) {

      newPtr->nextPtr = *sPtr;

      *sPtr = newPtr;

    }

    else {

      previousPtr->nextPtr = newPtr;

      newPtr->nextPtr = currentPtr;

      } /* end else */

  }

  else {

    printf( "%c not inserted. No memory available.\n", value );

  }

}

char delete( ListNodePtr *sPtr, char value )

{

  /* delete first node */

  if ( value == ( *sPtr )->data ) {

    ListNodePtr tempPtr = *sPtr;

    *sPtr = ( *sPtr )->nextPtr;

    free( tempPtr );

    return value;

   }

   

  else {

    ListNodePtr previousPtr = *sPtr;

    ListNodePtr currentPtr = ( *sPtr )->nextPtr;

 

   while ( currentPtr != NULL && currentPtr->data != value ) {

     previousPtr = currentPtr;

     currentPtr = currentPtr->nextPtr;

   }

   if ( currentPtr != NULL ) {

     ListNodePtr tempPtr = currentPtr;

     previousPtr->nextPtr = currentPtr->nextPtr;

     return value;

    }

   }

   return '\0';

}

int isEmpty( ListNodePtr sPtr )

{

  return sPtr == NULL;

}

void printList( ListNodePtr currentPtr )

{

  if ( currentPtr == NULL ) {

    printf( "List is empty.\n\n" );

   }

  else {

    printf( "The list is:\n" );

  while ( currentPtr != NULL ) {

    printf( "%c --> ", currentPtr->data );

    currentPtr = currentPtr->nextPtr;

   }

  printf( "NULL\n\n" );

   }

}

Answer 1

#include <stdio.h>

#include <stdlib.h>

typedef struct listNode

{

char data;

struct listNode * nextPtr;

} * TListNode;

typedef struct listNode _TListNode;

typedef struct listNode ListNode;

typedef ListNode *ListNodePtr;

#define LIST_NODE_SIZE (sizeof(listNode))

typedef struct _TQueue

{

TListNode first;

TListNode last;

int count;

} * TQueue;

#define QUEUE_SIZE (sizeof(struct _TQueue))

void Queue_Init(TQueue q)

{

q->first=q->last=NULL;

q->count=0;

}

int Queue_Push(TQueue q, char chChar)

{

int iReturn=0;

TListNode newNode = (TListNode) malloc(LIST_NODE_SIZE);

if (newNode != NULL)

{

newNode->data = chChar;

newNode->nextPtr = NULL;

if (q->count==0)

{

q->first = q->last = newNode;

}

else

{

q->last->nextPtr = newNode;

q->last = q->last->nextPtr;

}

q->count++;

}

else

{

iReturn = -1;

}

return(iReturn);

}

char Queue_GetFirst(TQueue q )

{

return(q->first->data);

}

char Queue_GetLast(TQueue q)

{

return(q->last->data);

}

int Queue_Pop(TQueue q)

{

int iReturn=0;

if (q->count>1)

{

TListNode temp = q->first;

q->first = q->first->nextPtr;

free(temp);

q->count--;

}

else if (q->count==1)

{

free(q->first);

q->first=q->last = NULL;

q->count=0;

}

else

{

iReturn=-1;

}

return(iReturn);

}

void Queue_Destroy(TQueue q)

{

TListNode listNodePtr = q->first;

for (int iLoop=0; iLoop<q->count; iLoop++)

{

q->first = q->first->nextPtr;

free(listNodePtr);

listNodePtr = q->first;

}

q->first=q->last=NULL;

q->count=0;

}

Queue_Dump( TQueue q, char * strMsg)

{

if (strMsg!=NULL)

{

printf("******************************************************\n");

printf(strMsg);

}

printf("******************************************************\n");

TListNode cur = q->first;

while (cur!=NULL)

{

printf(" %c \n",cur->data);

cur = cur->nextPtr;

}

}

int main()

{

struct _TQueue queue;

char chChar;

Queue_Init(&queue);

for (chChar='A'; chChar<='Z'; chChar++)

{

Queue_Push(&queue,chChar);

}

int N = queue.count;

char strMsg[25];

sprintf(strMsg," queue count = %d \n",N);

Queue_Dump(&queue,strMsg);

for (int iLoop=0; iLoop<N; iLoop++)

{

printf(" popping %c .....\n",Queue_GetFirst(&queue));

Queue_Pop(&queue);

}

if (queue.count==0)

{

printf("DONE \n");

}

}