Thread: delete function

Originally Posted by G4143

There isn't a mistake in your diagram. There is a shortcoming in your understanding of C's call by value mechanism.

Understand how C passes values to functions and you'll see what you have to do.

This is what I understand call by value and call by address

Code:

  #include<stdio.h>

void bar ( int fvar)
{
    fvar++;
}
void foo ( int *ptr)
{
    *ptr = 1000;      // This line change value of y 
}
int main()
{
    int x = 1;
    int y = 100;
    printf(" value of x before to functional call is %d \n", x);
    printf(" value of y before to functional call is %d \n", y);
    bar (x) ;        // pass value of variable x to function bar 
    printf(" value of x after function call is %d \n", x);
    foo (&y);        // pass address of variable y to function foo
    printf(" value of y after to function call is %d \n", y);
    
    return 0;
}

Output

Code:

 


 value of x before to functional call is 1
 value of y before to functional call is 100
 value of x after function call is 1
 value of y after to function call is 1000

Originally Posted by flp1969

OF COURSE there is a mistake.... Build the diagram step by step, following what the code is doing!!!

This what I understand up to 4 nodes

Originally Posted by Kittu20

This what I understand up to 4 nodes

And what are you doing on delete()?

Kittu20: What exactly do you want your delete function to do? That is, what do you expect the "current" parameter to be? Is it always the head of the list, so you can delete only the first node in a list? If that's the case then it's a very easy task.

First define exactly what the function does and what the function's parameters are supposed to mean, and then design and write the function. If you do it in the other order, you're gonna have a bad time.

Originally Posted by flp1969

And what are you doing on delete()?

You told me to draw a procedure to delete node in list on paper, I did that first.

After that how to insert node in the list, you asked to make it on paper, I did that too.

i don't know what's wrong with my drawing. as i said before i don't see anything wrong. can you please point out my mistake so that i can think about it.

Originally Posted by christop

Kittu20: What exactly do you want your delete function to do? That is, what do you expect the "current" parameter to be? Is it always the head of the list, so you can delete only the first node in a list? If that's the case then it's a very easy task.

First define exactly what the function does and what the function's parameters are supposed to mean, and then design and write the function. If you do it in the other order, you're gonna have a bad time.

I want to create a function that can delete any node from the list. but i am struggling to write the function. If you ask me to delete any node in my list, I can show it on paper.

Originally Posted by Kittu20

I want to create a function that can delete any node from the list. but i am struggling to write the function. If you ask me to delete any node in my list, I can show it on paper.

OK, then show on paper how you would delete any node in the list. Then you will see what information you need to give to your function for it to do its job.

Originally Posted by christop

OK, then show on paper how you would delete any node in the list. Then you will see what information you need to give to your function for it to do its job.

I have already done please look at image in my previous post where i am deleting the current node form list

I see a diagram in #12, but it's deleting only the first node (what you misleadingly call the "current" node). Again, how would you delete any node in the list, not just the first node?

Originally Posted by christop

I see a diagram in #12, but it's deleting only the first node (what you misleadingly call the "current" node). Again, how would you delete any node in the list, not just the first node?

In figure, I am showing what will be the list if one specific node delete from five nodes

Originally Posted by Salem

Your first task is to make delete just find the element to delete.

You'll need
- a while loop
- an if statement
- and printf("Found node containing %d\n", value);

Don't try to delete the node yet, just make sure your code is right at just being able to find the node to delete.
Baby steps.

Done it

Code:

 #include<stdio.h>#include<stdlib.h>
 
struct node
{
    int data;
    struct node *next;
};
 
void delete( struct node **current, int value)
{
	struct node *temp = *current;
	
    while (temp != NULL)
	{
		if ( temp -> data == value)
		{		
			printf("Found node containing %d\n", value);
		}
		temp = temp->next;  
	}
}


void instert( struct node **current, int value)
{
    struct node *new = malloc(sizeof(struct node));
     
    if ( new != NULL)
    {
        new-> data = value;
        new -> next = *current;
        *current = new;
    }
}
 
void List(struct node *current)
{
    while (current !=NULL)
    {
        printf("%d -> ", current -> data);
        current = current -> next;
    }
    printf("NULL\n");
}
 
 
int main ()
{
    struct node *head = NULL;   
     
    instert(&head, 1); 
    instert(&head, 2);
    instert(&head, 3);
    instert(&head, 4);
    instert(&head, 5);
    List(head);
    delete (&head,4);
    List(head);
    delete (&head,3);
    List(head);
    delete (&head,5);
 //   List(head);
    printf("\n");
    return 0;
}

Code:

5 -> 4 -> 3 -> 2 -> 1 -> NULLFound node containing 4
5 -> 4 -> 3 -> 2 -> 1 -> NULL
Found node containing 3
5 -> 4 -> 3 -> 2 -> 1 -> NULL
Found node containing 5

Originally Posted by Salem

OK, now in the delete function, also print out whether the found node is the head node, or one of the other nodes.

The head node is special, it takes extra care to delete it, so you need to know which it is.

exactly at this stage i'm having trouble. I am getting the position of the node by comparing the data value.

Can the position of a node be detected without comparing the data value, if yes how?