Delete a node in a linear link list. We can delete a node from different position of the list depend on position or value. The type of deleting node are

1. Delete from beginning.
2. Delete from end
3. Delete from a said position except first and last
4. Delete from any position
5. Delete a node after a value
6. Delete a node before a value

Now we create the basic environment of the link list.

#include<stdio.h>
#include<conio.h>
struct slinearlinklist
{
	int i;
	struct slinearlinklist *next;
};
typedef struct slinearlinklist node;

//prototype declaration

node *delete_first(node *);
void delete_end(node *);
void delete_pos1(node *,int);
node *delete_pos2(node *);
node *delete_after(node *);
node *delete_before(node *);

node *head=NULL;

int main()
{
	int c,i,pos;
	while(1)
	{
		printf(" 8. Delete From begining\n");
		printf(" 9. Delete From end position\n");
		printf("10. Delete from a said position except first and last\n");
		printf("11. Delete From position [Any where]\n");
		printf("12. Delete a node after a said value\n");
		printf("13. Delete a node before a said value\n");
		printf("25. Exit\n");
		printf("Enter Your choice : ");
		scanf("%d",&c);
		switch(c)
		{

			case 8:
				head=delete_first(head); // Delete From beginning
				break;
			case 9:
				delete_end(head); // Delete From end
				break;
			case 10:
				printf("Enter position : ");//Delete From a said position except first and last
				scanf("%d",&pos);
				delete_pos1(head,pos);
				break;
 			case 11:
				printf("Enter position : ");//Delete From anywhare
				scanf("%d",&pos);
				delete_pos2(head,pos);
				break;
			case 12:
				head=delete_after(head); // Delete after a value
				break;
			case 13:
				head=delete_before(head); // Delete before a value
				break;
			case 8:
				exit(0);
		}
	}
}

Delete a node from begining

Delete a node from the beginning of the exsiting list. As it change the first node, it return a node pointer.

node *delete_first(node *l)
{
	node *temp;
	if(l!=NULL)
	{
		temp=l;
		free(l);
		l=temp->next;
	}
	return l;
}

Delete a node from end

Delete a node from the beginning of the exsiting list. As it change the first node, it return a node pointer.

void delete_end(node *l)
{
	if(l!=NULL)
	{
		while(l-<next->next!=NULL)
		{ 
			l=l->next;
		}
		free(l->next);
		l->next=NULL;
	}
}

Delete from a said position except first and last

void delete_pos1(node *l,int pos)
{
	node *temp;
	int i;
	if(l!=NULL)
	{
		for(i=1;i<=pos-2;i++)
		{ 
			l=l->next;
		}
		temp=l->next->next;
		free(l->next);
		l->next=temp;
	}
}

Delete from a said position [Any Position]

node *delete_pos2(node *l)
{
	node *temp;
	int pos,i,c;
	node *h=l;
	printf("Enter position : ");
	scanf("%d",&pos);
	c=count(l);	
	if(pos==1)
	{
		//first delete
		h=del_first(l);
		return h;
	}
	else if(c==pos)
	{
		//end delete
		del_end(l);
		return h;
	}
	else if(c<pos)
	{
		printf("Your position is larger than list");
	}
	else
	{
		//position delete
		del_pos(l,pos);
		return h;
		
	}
}

Delete a node after a said value

node *delete_after(node *l)
{
	node *temp,*h;
	int val;
	int fl=0,pos=0;
	h=l;
	if(l!=NULL)
	{
		pos=1;
		printf("Enter a value(after we delete a node)");
		scanf("%d",&val);
		while(l->next!=NULL)
		{
			if(l->i==val)
			{
				fl=1;
				break;
			}
			pos++;
			l=l->next;
		}
		if(fl)//found
		{
			if(l->next==NULL)//last node   delete_pos2
			{
				printf("data found at Last Node");
			}
			else
			{
				delete_pos2(h,++pos);
			}			
		}
		else//not found
		{
			printf("Supplied data not found");
		}
		return h;
	}
}

Delete a node before a said value

node *delete_before(node *l)
{
	node *temp,*h;
	int val;
	int fl=0,pos=0;
	h=l;
	if(l!=NULL)
	{
		pos=1;
		printf("Enter a value(after we delete a node)");
		scanf("%d",&val);
		while(l->next!=NULL)
		{
			if(l->next->i==val)
			{
				fl=1;
				break;
			}
			pos++;
			l=l->next;
		}
		if(fl)//found
		{
			if(l->next==NULL)//last node   delete_pos2
			{
				printf("data found at Last Node");
			}
			else
			{
				delete_pos2(h,pos);
			}			
		}
		else//not found
		{
			printf("Supplied data not found");
		}
		return h;
	}
}