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#include<stdio.h>
 
struct node
{
       int info;
       struct node * next;
}*start, *rear, *temp;
 
 
void INS(int item)
{
 
struct node *newnode;
newnode = (struct node *) malloc ( sizeof(struct node) );
 
if(newnode==NULL)
printf(" NO SPACE LEFT ");
else
{
    
newnode->info=item;
newnode->next=NULL;
 
if( start == NULL )
{ 
start=newnode;
rear=newnode;
}
else // INS at END
{ 
rear->next = newnode;
rear=rear->next;
}
 
} //end of outer if
}// end of func
 
void DEL()
{
 
if(start==NULL)
printf("\n No item to delete. Queue is empty. \n");
else
{
 
printf("\n Node with Info = %d is Deleted. \n", start->info );
temp=start;
start=start->next;
free(temp);
 
}
 
}
 
void DISPLAY()
{
if(start==NULL)
printf("\n Queue is empty. No Nodes. ");
else
{
temp=start;
 
printf("\n |");
while(temp!=NULL)
{
printf(" - |%d|", temp->info);
temp=temp->next;
}
printf(" - | \n");
}//end of else
}     
 
int main()
{
    int item,ch=1;
    start=rear=NULL;
 
    
   while(ch!=4)
    {
    printf("\n MENU: \n");
    printf(" 1. Insert a node. ");
    printf("\n 2. Delete a node. ");
    printf("\n 3. Display Queue. ");
    printf("\n 4. EXIT \n Your Choice: ");
    scanf("%d",&ch);
    
    switch(ch)
    {
    case 1: //INSERT
        
    printf("\n ENTER ITEM: ");
    scanf("%d", &item);
    
    INS(item);
    break;
    
    case 2: //DELETE
    DEL();
    break;
    
    case 3: //DISPLAY
    DISPLAY();
    break;
    
    case 4: 
    printf("\n Exiting.. ");
    break;
    
    default: printf(" INVALID CHOICE. ");
    
    }
    
    }; //end of while loop
    
    return 0;
    
}