Enter (+) integers and terminate it by 0
1
2
3
0
The list is: 1 2 3 

3 items were entered to the list
Sum of the items are: 6
Enter a integer to check is it in the list:2
2 is in the list
The list is: 1 2 3 
Enter a number to delete it from the list:2
The list is modified
The list is: 1 0 3

/*Function to delete a specific number from the list*/
void delete(int n, node_ptr list)
{
	node_ptr tmp;
	node_ptr current = list->next;
	int number;
	
	printf("Enter a number to delete it from the list:");
	scanf("\n%d",&number);
	
	while(current != NULL)
	{
		if(current->data_item == number)
		{
			tmp = current->next;
			free (current);
			current = tmp;
			printf("The list is modified\n");
			break;
		}
		else
		{
			current = current->next;
		}
	}
	if(current == NULL )
	{
		printf("%d is not in the list\n", number);
	}
	return;

#include <stdio.h>
#include <stdlib.h>
#include "1.h"

/*Function to create an empty List*/
node_ptr create(void)
{
	node_ptr list=(node_ptr)malloc(sizeof(struct node));
	list->data_item = 0;/*The first node*/
	list->next = NULL; /*the last node*/
	return list;
}
/*Function to return dynamically allocated memory in list*/
void destroy(node_ptr list)
{
	node_ptr current = list;
	
	while(current)
	{
		node_ptr to_free = current;
		current = current -> next;
		free(to_free);
	}
}
/*Function to insert n at front of list*/
void insert_at_front(int n, node_ptr list)
{
	node_ptr new_node= (node_ptr)malloc(sizeof(struct node));
	new_node -> data_item = n;
	new_node -> next = list-> next;
	list -> next = new_node; 
}
/*Function to print list*/
void print(node_ptr list)
{
	node_ptr current = list -> next;
	printf("The list is: ");
	while(current)
	{
		printf("%d ", current->data_item);
		current = current->next;
	}
	printf("\n");
}
/*Function  to insert n in  ( non decreasing ) order in list - assuming list items are already in ( non decreasing ) order. */
void insert_in_order(int n, node_ptr list)
{
	node_ptr before = list;
	node_ptr new_node = (node_ptr) malloc(sizeof(struct node));
	new_node-> data_item = n;
	
	while(before-> next && (before->next->data_item < n))
	{
		before = before->next;
	}
	new_node->next = before-> next;
	before->next = new_node;
}
/*Function  to find the number of items in the list*/
int length(node_ptr list)
{
	node_ptr current = list->next;
	int r = 0;
	while(current)
	{
		r++;
		current = current->next;
	}
	printf("\n%d items were entered to the list", r);
	return r;
}
/*Function to sum the integer values in the list*/
int sum(node_ptr list)
{
	node_ptr current = list->next;
	int t = 0;
	while(current)
	{
		t = t + current->data_item;
		current = current->next;
	}
	printf("\nSum of the items are: %d\n", t);
	return t;
}
/*Function to find a specific number in the list*/
node_ptr find(int n, node_ptr list)
{
	node_ptr current = list->next;
	int number=0;
	
	printf("Enter a integer to check is it in the list:");
	scanf("\n%d",&number);
		
	while(current != NULL)
	{
		if(current->data_item == number)
		{
			printf("%d is in the list\n", number);
			break;
		}
		else
		{
			current = current->next;
		}
	}
	if(current == NULL)
	{
		printf("%d is not in the list\n", number);
	}
	return current;
}
/*Function to delete a specific number from the list*/
void delete(int n, node_ptr list)
{
	node_ptr tmp;
	node_ptr current = list->next;
	int number;
	
	printf("Enter a number to delete it from the list:");
	scanf("\n%d",&number);
	
	while(current != NULL)
	{
		if(current->data_item == number)
		{
			tmp = current->next;
			free (current);
			current = tmp;
			printf("The list is modified\n");
			break;
		}
		else
		{
			current = current->next;
		}
	}
	if(current == NULL )
	{
		printf("%d is not in the list\n", number);
	}
	return;
}

tmp = current->next;
free (current);
current = tmp;

node_ptr before = list;
before -> next = current-> next;
current = before -> next;
free(current);

Node* current = first;
Node* previous = NULL;
while (current != NULL) {
    //...
    previous = current;
    current = current->next;
}

void delete(int n, node_ptr list)
{
	node_ptr previous = NULL;
	node_ptr current = list->next;
	int number;
	
	printf("Enter a number to delete it from the list:");
	scanf("\n%d",&number);
	
	while(current != NULL)
	{
		if(current->data_item == number && previous->next->data_item != 0)
		{
			previous = current;
			previous -> next = (current->next)->next;
			current = current -> next;
			free(current);
			printf("The list is modified\n");
			break;
		}
		else
		{
			current = current->next;
		}
	}
	if(current == NULL )
	{
		printf("%d is not in the list\n", number);
	}
	return;
}

Enter (+) integers and terminate it by 0
1
2
3
0
The list is: 1 2 3 

3 items were entered to the list
Sum of the items are: 6
Enter a integer to check is it in the list:3
3 is in the list
The list is: 1 2 3 
Enter a number to delete it from the list:3
Segmentation fault

foo *prev = NULL, *curr = list;
while( curr )
{
    ... check to see if this is what you need...
        ... handle appropriately ...

    ... fix up your pointers ...
    prev = curr;
    curr = curr->next;
}

void delete(int n, node_ptr list)
{
	node_ptr previous = list;
	node_ptr current = list->next;
	
	printf("Enter a number to delete it from the list:");
	scanf("\n%d",&n);
	
	while(current != NULL)
	{
		if(current->data_item == n)
		{
			previous->next = current->next;
			free(current);
			printf("The list is modified\n");
			break;
		}
		else
		{
			previous = current;
			current = current->next;
		}
	}
	if(current == NULL )
	{
		printf("%d is not in the list\n", n);
	}
	return;
}