Talk:Singly-linked list/Element removal

Needs description and goal

This needs a task description and goal. While it may be a valuable addition to have such a task, this does not yet meet minimum criteria. See Singly-linked_list/Element_insertion for possible verbiage (edited to suit) --Thundergnat (talk) 16:20, 27 October 2016 (UTC)

Taste

In a 2016 TED talk, interview with Chris Anderson, Linus Torvalds provides an example of element removal in a singly-linked list while discussing good taste in coding. He got rid of the if ... then statement to handle a special case. See at 15'40" in the talk. <lang C> remove_list_entry(entry) { // The "indirect" pointer points to the // *address* of the thing we'll update

indirect = &head;

// Walk the list, looking for the thing that // points tot the entry we want to remove

while ((*indirect) != entry) indirect = &(*indirect)->next;

// .. and just remove it

• indirect = entry->next;

} </lang> Slightly adapted to make the above code compile and run. <lang C>

1. include <stdio.h>

typedef struct node {

   int val;
   struct node* next;

} node_t;

node_t* head = NULL; node_t** indirect;

void remove_list_entry(node_t* entry) { // The "indirect" pointer points to the // *address* of the thing we'll update

indirect = &head;

// Walk the list, looking for the thing that // points tot the entry we want to remove

while ((*indirect) != entry) indirect = &(*indirect)->next;

// .. and just remove it

• indirect = entry->next;

}

int main() {

   head = malloc(sizeof(node_t));
   head->val = 1;
   head->next = malloc(sizeof(node_t));
   head->next->val = 2;
   head->next->next = NULL;
   remove_list_entry(head);
   return 0;

} </lang>

Visual Basic .NET of Tastefull

The Visual Basic .NET Tastefull version doesn't work if entry equals head, because head is a separate variable. In Torvalds c version the memory address head points to is altered. Dedalus (talk) 16:47, 30 November 2018 (UTC)