Thread: why float value in structute can be used for linkedlist ???

Originally Posted by Salem

None at all.

A float in a struct is no different to a normal float variable.

I'm not talking about 'float in structure', it's 'float in structure which is used in linked-list'.

if you are accepting a floating value in a structured float variable i.e. using 'scanf', of course in dynamically allocated space (for linked-list), the program terminates unusually.

I'm using Turbo c++ editor and haven't tried on other editors, so, is it a problem of editor ?

May want to get yourself another IDE. Floats can be used in linked list as the data.

Originally Posted by Syscal

May want to get yourself another IDE. Floats can be used in linked list as the data.

I'm sorry, but you are not getting my problem.

First thing is I'm using turbo c++ editor

I know that float can be used in linked-list , i said that if i am accepting a floating value using scanf function in a float variable declared in structure in a dynamically allocated space(such as linked-list), the problem occurs

thanks for the reply

Well have you got any code with an example of your problem?

I would guess that it probably has something to do with accessing structure element using '.' vs. '->', or putting the '&' to denote address-of, which the OP is doing wrong.

here is the code which works if "marks" is declared as an "int" and using format specifier "%d" instead of "%f"
tested on turbo c++ editor only

Code:

#include<stdio.h>
#include<conio.h>
#include<alloc.h>

typedef struct LinkedList
{
   int roll;
   float marks;
   char name[20];

   struct LinkedList *next;
}Node;

Node* CreateNode()
{
	Node *temp;

	temp=(Node*)malloc( sizeof(Node) );

	printf("\n\t\tEnter roll no : ");
	scanf("%d",&temp->roll);
	printf("\n\t\tEnter name : ");
	flushall();
	gets(temp->name);
	printf("\n\t\tEnter Marks : ");
	scanf("%f",&temp->marks);

	temp->next=NULL;

	return temp;
}
Node* AddNode(Node *head)
{
	Node *newnode,*temp;
	temp=head;

	newnode=CreateNode();
	if(head==NULL)
	{
		head=newnode;
	}
	else
	{
		while(temp->next!=NULL)
			temp=temp->next;

		temp->next=newnode;
	}

	return head;
}
void Display(Node *head)
{
	Node *temp;
	temp=head;

	printf("\n\nRoll no    Name \t\tMarks\n");

	while(temp!=NULL)
	{
		 printf("\n %d\t   ",temp->roll);

		 cputs(temp->name);

		 printf("\t  %f ",temp->marks);

		 temp=temp->next;
	}
	printf("\n\n");
}

void Displayrev(Node *temp)
{
	if(temp->next!=NULL)
		Displayrev(temp->next);

	 printf("\n %d\t   ",temp->roll);

	 cputs(temp->name);

	 printf("\t  %f ",temp->marks);
}

Node* Delete(Node *head)
{
	int option,r;
	Node *temp,*previous;

	temp=head;

	printf("\n\t\tEnter option. \n\t\t1. Delete first record\n\t\t");
	printf("Delete a particular record.\n\t\t3.Delete last record\n");
	scanf("%d",&option);

	switch(option)
	{
		case 1:
				head=head->next;
				free(temp);
				break;
		case 2:
				printf("\nEnter roll no. to delete the record: ");
				scanf("%d",&r);

				while(r!=temp->roll)
				{
					previous=temp;
					temp=temp->next;
				}
				previous->next=temp->next;
				free(temp);
				break;

		case 3:
			   while(temp->next!=NULL)
			   {
				 previous=temp;
				 temp=temp->next;
			   }
			   previous->next=NULL;
			   free(temp);
			   break;
	}

	return head;
}
Node* Insert(Node *head)
{
  int option,pos,loc=1;
  Node *temp,*newnode;
  temp=head;

  newnode=CreateNode();

  printf("\n\t\tEnter option. \n\t\t1. Insert at begining.\n\t\t2. Insert ");
  printf("at particular position.\n\t\t3.Insert at end\n");
  scanf("%d",&option);

  switch(option)
  {
	case 1:
			newnode->next=temp;
			head=newnode;
			break;
	case 2:
			printf("\nEnter Position at which you want to insert record \n");
			scanf("%d",&pos);

			while(loc!=pos-1)
			{
				  temp=temp->next;
				  loc++;
			}

			newnode->next=temp->next;
			temp->next=newnode;
			break;

	case 3:
			while(temp->next!=NULL)
				temp=temp->next;

			temp->next=newnode;
			break;
	}

	return head;
}

void Search(Node *head)
{
	Node *move;
	int r,flag=0;
	move=head;

	if(head==NULL)
		printf("\nHmmmmm .... Linked List is not yet created!!!!");
	else
	{
		printf("\nEnter Id\n");
		scanf("%d",&r);
		while(move!=NULL)
		{
			if(move->roll==r)
			{
					printf("\nRecord found\n");
					flag=1;

					printf("\n\nRoll no    Name \t\tMarks\n");

					printf("\n %d\t   ",move->roll);
					cputs(move->name);
					printf("\t  %f ",move->marks);
			 }
			   move = move->next;
		}
		if(move==NULL && flag==0)
			printf("\nRecord not found !!!\n");
	 }
}

Node* Modify(Node *head)
{
	Node *move;
	int r,flag=0;
	move=head;

	if(head==NULL)
		printf("\n\nRecord is not yet created !!!");
	else
	{
		printf("\nEnter Roll no : ");
		scanf("%d",&r);
		while(move!=NULL)
		{
			if(move->roll==r)
			{
				printf("\n\t\tEnter roll no : ");
				scanf("%d",&move->roll);
				printf("\n\t\tEnter name : ");
				flushall();
				gets(move->name);

				printf("\n\t\tEnter Marks : ");

				scanf("%f",&move->marks);

				flag=1;
			 }
			   move = move->next;
		}
		if(move==NULL && flag==0)
			printf("\nNode not found !!!\n");
	 }
	 return head;
}

void Freeall(Node *head)
{
	Node *temp=head;

	while(temp!=NULL)
	{
	   head=head->next;
	   temp->next=NULL;
	   free(temp);
	   temp=head;
	}
}

void main()
{
	int option,roll,ch;
	Node *head=NULL;
	clrscr();

	do
	{
	printf("\n\n**************************** STUDENT DATABASE ****************************");
	printf("  \n\n\t\t\t 1.Add Record\n\t\t\t 2.Delete Record \n\t\t\t 3.Insert Record \
		  \n\t\t\t 4.Display Record \n\t\t\t 5.Search Record \n\t\t\t 6.Modify  \
		  \n\t\t\t 7.Freeall \n\t\t\t 8.Exit \n\n\t\t\t ");
	scanf("%d",&option);
	switch(option)
	{
		case 1:
				head=AddNode(head);
				break;
		case 2:
				head=Delete(head);
				break;
		case 3:
				head=Insert(head);
				break;
		case 4:
				if(head==NULL)
				{
					printf("\n\nRecord is Empty !!!");
					break;
				}

				printf("\n\n1:Display serially  \n\n2:Display Reverse \n\n");
				scanf("%d",&ch);

				printf("\n\nRoll no    Name \t\tMarks\n");

				switch(ch)
				{
					case 1:
						Display(head);
						break;

					case 2:
						Displayrev(head);
						break;

					default:
						printf("\n\nInvalid Choice !!!");

				 }
				break;


		case 5:
				Search(head);
				break;
		case 6:
				head=Modify(head);
				break;
		case 7:
				Freeall(head);
				head=NULL;
				break;
	}

	}while(option!=8);

	getch();
}

I wonder if scanf first assumes double??? If you used a temporary variable first, then assigned it to the structure element, you'd be doing an implicit conversion from double to float somewhere along the line as needed. However, inputting directly to the structure element from scanf() might overwrite some adjacent data if the default is double. Still sounds like a compiler bug.

In his book Expert C Programming, Peter van der Linden mentions a similar type of problem that is the result of Borland's compilers not quite being smart enough to know when to provide floating point support. His suggested workaround is to add the following function:

Code:

static void forcefloat(float *p)
{ float f = *p; forcefloat(&f); }

Never call this, of course.

It's worth a try, I guess, but as has been suggested, stop using Turbo C. There's no need, unless your school/instructor is so backward that it's required.

thanks to all of you people for your suggestions, it will definitely help me

thanks a lot