Singly-linked list/Element removal: Difference between revisions

=={{header|C++}}==

<lang cpp>#include <iostream>

// define a singly linked list

struct link

{

link* next;

int data;

link(int newItem, link* head)

: next{head}, data{newItem}{}

};

void PrintList(link* head)

{

if(!head) return;

std::cout << head->data << " ";

PrintList(head->next);

}

link* RemoveItem(int valueToRemove, link*&head)

{

// walk the list to look for the node conaining the value including

// the head node itself

for(link** node = &head; *node; node = &((*node)->next))

{

if((*node)->data == valueToRemove)

{

// the item was found; remove it and return its node

link* removedNode = *node;

*node = removedNode->next;

removedNode->next = nullptr;

return removedNode;

}

}

// the node was not found in the list

return nullptr;

}

int main()

{

// link some nodes into a list

link link33{33, nullptr};

link link42{42, &link33};

link link99{99, &link42};

link link55{55, &link99};

link* head = &link55;

std::cout << "Full list: ";

PrintList(head);

std::cout << "\nRemove 55: ";

auto removed = RemoveItem(55, head);

PrintList(head);

std::cout << "\nThe removed item: ";

PrintList(removed);

std::cout << "\nTry to remove -3: ";

auto removed2 = RemoveItem(-3, head);

PrintList(head);

if (!removed2) std::cout << "\nItem not found\n";

}</lang>

{{out}}

<pre>

Full list: 55 99 42 33

Remove 55: 99 42 33

The removed item: 55

Try to remove -3: 99 42 33

Item not found</pre>