How to pass a linked list to a function in c This will allow this function to modify the address held by the caller - i. Net and Node. Compared to std::forward_list this container provides bidirectional iteration capability while being less space efficient. Understanding Node Structure In a singly linked list, each node consists of two parts: data and a Jul 23, 2025 · The new node is always added before the head of the given Linked List. Discover effective ways to pass a linked list as an argument to a function in C, troubleshoot common pointer issues, and optimize your code for better perfor Nov 11, 2025 · I am writing a program which creates a linked list. But in many common cases, LinkedList hinders performance. g. These items are connected using pointers in a sequential manner. e. Oct 21, 2025 · Following is the approach to add a new node at the end of the linked list: Create a new node and set its next pointer as NULL since it will be the last node. Essentially we are saying that the name freeFunction will be used to mean “a pointer to a function that returns void and accepts a single void * argument containing the item to be freed I implemented a singly linked list a couple hours ago (just for fun). Data is stored in non-contiguous memory, allowing fast insertion and deletion anywhere in the list (beginning, middle, or end). Our first node is where head points and we can Aug 4, 2021 · Learn to modify the head pointer of a linked list in C. Therefore, the function for adding an element will also be called push_back. a. Lists in LISP Although cons cells can be used to create lists, however, constructing a list out of nested cons function calls can't be the best solution. To maintain sequential ordering, every list element includes two links: one that points to the previous element another that points to the next element C++ STL list implementation In C++, the STL list implements the doubly-linked list data structure. Method 1: Traverse the whole linked list and count the no Aug 28, 2025 · After determining the total count, traverse the list again and stop at the (count/2)th node to return its value. Here's what's Nov 5, 2019 · Generic Linked List in C A simple approach using void pointers I’m a full-stack developer, writing web application mainly in . Sep 11, 2024 · Approach: The idea is very simple, first find the last node of the first linked list. Jul 23, 2025 · A linked list is a fundamental data structure in computer science. We can always pass the head pointer as an argument and traverse/update the list. k. May 10, 2017 · Your function print_list expects an argument of type node_t * but you are passing node_t **. Implemented as a doubly linked list and maintains both front and back for fast operations on both the ends. For example, if it was not passed by reference, and you passed head (initialized to NULL), to the push function, a new item would be created, but your value Linked lists are a data structure that can be used to solve these problems, and we discuss in this chapter how can we do so. Each node of the list stores 4 data about, a patient. Attach a singly linked Mar 29, 2022 · After arrays, the second most popular data structure is Linked List. Sep 11, 2025 · A LinkedList<T> in C# is a doubly linked list that allows fast insertion and deletion of elements at any position. Adding an Element to a Linked List in C We use the Linked List class from the C++ STL as a model. Each node contains two pieces of information: Some piece of data that is stored in the sequence A link to the next node in the list We can traverse the list by starting at the first node and repeatedly following its link. c define function stubs (a. This is the structure I used: typedef struct node { int data; struct node *next; } node; and these are the declarations of my basic functions: /* * insert: creates and inserts a new node (storing data) in the list pointed by * the pointer stored at address head. In the LinkedList, certain operations do not require the whole collection to be copied. Insert a Node: Write a function that adds a new node to the end of the list. As you know, Linked lists have pointers pointing to its next element (singly linked list) and previous element (double linked list). For example, if the given Linked List is 10->15->20->25 and we add an item 5 at the front, then the Linked List becomes 5->10->15->20->25. C++ List is a STL container that stores elements randomly in unrelated locations. What is a Sep 19, 2025 · A linked list is a type of linear data structure similar to arrays. In C, we can use the structure type to group the multiple data types in a single variable. The list function is rather used for creating lists in LISP. Introduction Linked lists are the best and simplest example of a dynamic data structure that uses pointers for its implementation. LinkedList<T> is a general-purpose linked list In src/linked_list. Essentially, linked lists C++ List A list is similar to a vector in that it can store multiple elements of the same type and dynamically grow in size. Before inserting any node, we had to dynamically allocate it first. The specific Count, GetNth, DeleteList, Pop, InsertNth, FrontBackSplit, RemoveDuplicates, MoveNode, SortedMerge, SortedIntersect, Reverse, and Oct 5, 2025 · A singly linked list is a fundamental data structure, it consists of nodes where each node contains a data field and a reference to the next node in the linked list. Program to Print the Singly Linked List using Recursion. h> //Defining a structure of the node struct node Jan 2, 2021 · l = reverse_list(l); print_list(l); } I've no problem with these functions; they work as expected, but the notion of pass by value and pass by reference confused me, when I tried to understand how the function takes list as a parameter and returns it. push_back(new Point()) it compiles. However, understanding pointers is crucial to understanding how linked lists work, so if you've skipped the pointers tutorial, you should go back and redo it. The dynamic memory allocation function known as malloc () is used to specify the size of node. Feb 24, 2014 · The reason you must pass head to the push function is because your push function is expecting to modify the value of the head pointer. If your linked list is a class that manages itself and keeps nodes out of your reach, just pass an instance by reference. The function must be supplied by the caller when they call list_new. We can then assign the pointer to a pointer variable of Jul 9, 2015 · The standard way to handle linked lists in C is to have the push and pop functions automatically update the head pointer. Sep 2, 2015 · How can I pass the head pointer of a link list to a function? I wrote 2 programs to insert 10 elements in a link list at the end. Sep 19, 2018 · Your additional list functions are just functions that iterate over each node in the list doing something with the information like printing the list or freeing all the nodes in the list. One of them runs successfully and other one does not. A similar function is called push_front and does exactly what you might guess, it adds the element in front instead of the back of the list. At each step, point the current node to its previous node and then move all three pointers forward until the list is fully reversed. I'm facing a problem that I face data loss during passing the linked list to add/sub/multiply functions because in these functions I delete added values from equations to the linked list. You need to pass your function 'the address of the address of the head' - or IntElement **head. Some functions like print data in a list or changing data of nodes in the list do not require changing the head pointer of the linked Adding an Element to a Linked List in C We use the Linked List class from the C++ STL as a model. util package. Something like (though it is not compilable): Dec 23, 2022 · In my print_ll function, I pass the head of the Linked List, and I was trying to use that while loop to walk through the linked list, but I noticed that tmp->next isn't NULL like it's declared in my init_ll () func. First, find the middle of the list and reverse the second half starting from the node after the middle. Problem Statement Delete a node with a given key from the given linked list and in case there are multiple occurrences of a given key in the linked list, then delete the first Aug 29, 2024 · Define a Node class/struct with data and a reference to the next node. Jan 3, 2009 · You can't do: List* list = &Function(arguments); IIRC, this tries to find the data address of the functionmake the function return a List* then just set the List* you are creating to the result of the function. Apr 26, 2025 · std::list is a container that supports constant time insertion and removal of elements from anywhere in the container. But there are also some cases where we can come up with a solution without modifying the head pointer of the linked list. h declare the interface (a. A node contains two things first is data and second is a link that connects it with another node. Having a good grasp of Linked Lists can be a huge plus point in a coding interview. If you read this far, thank the author to show them you care. Dynamic Size: LinkedList grows or shrinks dynamically at runtime. A linkedlist is a collection of nodes. In this article, you'll learn what linked lists are and when to use them, such as when you want to implement queues, stacks, or graphs. js stack. Initialize a pointer curr to head1 and move curr to the last node of the first linked list. In this article, we will learn how to print a linked list in C++. The emphasis is on the linked list algorithms rather than the features For some of the problems we present multiple dummy node vs. Create a node in the linked list In the previous section, we discussed how to create a linked list. Let me simply write a main for testing these and we'll see how things get mixed. In this article, let’s see how to implement a linked list in C. Set next of curr to head2. Fast random access is not supported. C is "Call by value" meaning copies of parameters are passed into functions. Change print_list(&head); to print_list(head); Jul 23, 2025 · It is generally easy to decide the prototype of functions of this category. In this article, we will explore how to split a linked list into two lists and merge two sorted lists using a function in the C programming language. This method requires two passes through the linked list to find the middle element. Learn how to create and manipulate them in this comprehensive guide. Since a Linked List is typically represented by the head pointer of it, it is required to traverse the list till the last A linked list is created using struct keyword and the nodes are defined in this structure. So, we got two types of functions. c create test function stubs for each linked list Jul 23, 2025 · Given a singly linked list, find the middle of the linked list. Jul 23, 2025 · The singly linked list is the simplest form of linked list in which the node contains two members data and a next pointer that stores the address of the next node. What is a linked list? A linked list is a chain of nodes, used to store a sequence of data. Unlink the portion of the list that needs to be reversed from the rest of the list. Mar 31, 2021 · int res = insert_l( one_job, new_jobs, compare_reference ); and if res is 0 one_job was inserted in new_jobs list at the correct position. Aug 29, 2015 · I have a question regarding passing the head of a linked list in C through a function. Then, update the next pointer of the last node to the head node the second linked list. List containers are implemented as doubly-linked lists; Doubly linked lists can store each of the elements they contain in different and unrelated storage locations. If you call it like mylist. Did your code compile? The function Create_List (node *curr) needs some arguments. In this article, I will explain how to create and traverse a linked list in C programming. 13. Oct 14, 2021 · Introduction The linked list is one of the most important concepts and data structures to learn while preparing for interviews. // Postcondition: A new node containing the given entry has been added at the head of the list; head_ptr now points to the head of the new, longer linked list. An academic-but-functional implementation of this can be found in this project at my University. Then it uses the AddLast and AddFirst methods to append or Hey I've set up some linked lists in a program i'm working on , but am having problems using functions with them. It is usually implemented as a doubly-linked list. Doubly linked list also starts from head node, but provide access both ways. So the code goes something like this: #include <stdio. We also discuss how to implement a linked list in C, and how to use it to solve problems. Linked List 2The standard template library provides a container for lists (it is a doubly linked lists). If your linked list is just you literally managing a bunch of nodes (getting your hands dirty and avoiding Object Oriented Design at all costs), then yeah you would pass the head. Jul 23, 2025 · A linked list is a linear data structure where each element (called a node) is connected to the next one using pointers. Aug 27, 2025 · [Naive Approach] Sequential insertion at the end of a linked list (using traversal) For each element of an array arr [] we create a node in a linked list and insert it at the end. deque to improve the performance of your linked lists and how to implement linked lists in your own projects. Thank you for reading. For example, the function print_list takes a single node as an argument (curr, short for current). h> // Define a structure for a node in linked list struct Node { int data; // Data of node struct Node* next; // Pointer to next node in list }; // Function to display a Jul 24, 2011 · The value of that address was passed to your function - not what was holding that address back at the caller. This blog explains different ways in which the head pointer of a linked list can be modified inside a C function. The create function creates the list, but because the list object is not returned to main, main cannot see the list. Reattach the reversed portion to the main list. Understand their types, operations, and implementation in a beginner-friendly way. Return head1. In this article, we will learn about the linked list, its types, representation of the linked list in C, and discuss what link list offers as compared to the similar data structures. Add This program invokes the LinkedList constructor. Unlike array, elements of linked list are stored in random memory locations. Jul 23, 2025 · The linked list allows the users to store data of the same type in non-contiguous memory locations through dynamic memory allocation. We will provide a detailed explanation of the code and include examples and use cases. To pass the list as a parameter, we only have to pass a reference to the first node. Implement a recursive function to insert a new node at the end of the list. * Returns the pointer of the new node or NULL if the process Jul 23, 2025 · Output: 10 20 30 Explanation: The linked list is created with nodes containing values 10, 20, and 30 in sequence. update the linked list to point to the new head. Engineering Computer Science Computer Science questions and answers apter 3 Linked Lists 11. The list function can take any number of arguments and as it is a function, it evaluates its arguments. However, two major differences between lists and vectors are: You can add and remove elements from both the beginning and at the end of a list, while vectors are generally optimized for adding and removing at the end. API) for the linked list module. And if at any time you need to use descending order or sort by another criteria you just need to pass a new function. Step-by-step approach: If head1 is empty, return head2. Method 1: Traverse the whole linked list and count the no Jul 23, 2025 · LinkedList in java is basically a part of the collection framework present in java. You'll also learn how to use collections. Jan 25, 2022 · LinkedList This C# generic type allows fast inserts and removes. Here, in this article, I try to explain the Recursive Function for Displaying a Linked List in C Language with Examples and I hope you enjoy this Recursive Function for Displaying a Linked List in C Language with Examples article. I want the function to modify the linked list. If the list is empty, this new node Sep 22, 2015 · Linked list creation and traversal is the stepping stone in data structures. The next of the last node is null, indicating the end of the list. Passing a linked list to a function I am trying to pass a pointer to a linked list to a function. Jul 23, 2025 · Given a singly linked list, find the middle of the linked list. Store the head reference in a temporary variable If the Linked List is empty, make the new node as the head and return Else traverse till the last node Change the next pointer of the last node to point to the new node Below is the Dec 8, 2016 · A linked list is a data structure that can store an indefinite amount of items. Aug 27, 2024 · Step-by-step approach : Find the start and end positions of the linked list by running a loop. Mar 21, 2017 · The problem is statement mylist. After the user decides to o I have single linked list filled with numbers which I send as argument to the function search_tnode. If function found number that I'm searching for it returns and in main I can use new list starting with that number. Create a Linked List in C Even the simplest linked list node needs to contain a pointer to the next and at least one data field. Each object is separately allocated. In src/linked_list. Jul 11, 2025 · LinkedList<T> class in C# is the part of the removal namespace. 3. Therefore, the Oct 9, 2014 · This method is supposed to take another linked list as a parameter, and add the contents of this linked list to the calling instance's linked list. This generic type allows fast inserting and removal of elements. If you don't pass it by reference, any changes to it will only be available within the function call. Sep 14, 2021 · Introduction The linked list is one of the most important concepts and data structures to learn while preparing for interviews. Insert a new node into a singly linked list (a) before and (b) after a node pointed to by p in this list (possibly the first or the last). push_back(4), in which you pass an integer whereas mylist expects a Point*. As a result, we can iterate both forward and backward. Aug 28, 2025 · Given the head of a singly linked list, determine whether the list contains a cycle. Oct 19, 2010 · Here's what i want: I want to create a linked list in the main function and pass its address to createRandomList so that function can actually fill out the list. It is the implementation of the LinkedList data structure that stores elements in a non-contiguous manner inside the memory. It implements a doubly-linked list data structure where elements are not stored in contiguous memory. local reference. And newly added node becomes the new head of the Linked List. In the last node of the linked list, the node may point at null or another special node named Tail. We can do so by using the malloc function. For example, if given linked list is 1->2->3->4->5->6 then the output should be 4. Wrapping Up In this article, I've explained: How a linked list works The pros and cons of a linked list How to implement a linked list with Python You can find the code for this article here. This means that you can use the same List-related functions to Oct 10, 2017 · The direct problem, as M. Then when thats done i want to pass the list as a copy to the function outputList () this last part seems to be working properly but i'd figure i'd add it in anyways. Jul 23, 2025 · There are two methods to copy the linked list into another linked list: Copy constructor Overloading the 'Assignment' operator Copy Constructor and Linked List A copy constructor is just like a constructor; it is a member function that is used to initialize a value to an object with the help of another object in the same class. Jul 11, 2025 · In this article, insertion in the list is done at the end, that is the new node is added after the last node of the given Linked List. May 2, 2013 · Line 5 declares a function pointer for a generic free function that will be called for each element in the list when it is destroyed. Let us call the function that adds at the front of the list is push (). Linked Lists support efficient insertion and deletion operations. the victim) is handled in the free_list function) Jun 21, 2024 · To define and work with a linked list in C, you need to understand the syntax and structure of the various components involved, such as the node definition, list operations, and function definitions. It is a collection of nodes that are linked with each other. Like any good collection, you want to be able to add and remove items from your list, as well as traverse the list to look at each item or to look for a particular item. Oct 3, 2013 · In this case you would want to keep a pointer to the last element of the list, as that would be the one that would point to the new one when it gets linked. Reverse the unlinked portion using the standard linked list reverse function. Jul 23, 2025 · Linked List linear collection of objects called nodes that are stored in the memory at random addresses. A linked list is a linear data structure, made of a chain of nodes in which each node contains a value and a pointer to the next node in the chain. Adding the elements should only be done if the element does not already exist. Nov 30, 2021 · I've seen many example of linked list in which double pointer is used in a function to add the node in list Code: void addNodetoList (struct Node **nod Sep 22, 2022 · We will work on solving a few questions on linked lists later on. Apr 7, 2021 · I have used doubly linked list (as required in the project), it works correctly as well as all functions. Nov 16, 2012 · 1 2 3 void list_head insert (node*& head_ptr, const node::value_type& entry); // Precondition: head_ptr is the head pointer of a linked list. While using the linked list in C programming, every node of a linked list is assigned a memory as soon as the malloc() function is called. The linked lists work fine as long as they stay in the main function : so they're not at fault struct node { int x; int y; node *next; }; is the linked list Jul 23, 2025 · Your All-in-One Learning Portal: GeeksforGeeks is a comprehensive educational platform that empowers learners across domains-spanning computer science and programming, school education, upskilling, commerce, software tools, competitive exams, and more. In test/test_linked_list. In the function, If I print out a member of the structure,it works,but if I try to print in main the program breaks,which leads me to think it has something to do with bad pointers. How to reverse a singly linked list in C. And we will learn more about this and singly linked lists in this tutorial. Linked lists consist of nodes, and is a linear data structure we make ourselves, unlike arrays which is an existing data structure in the programming language that we can use. For example, the following function that adds x to data members of all nodes. BTW: maybe you should write std::list or place a using std::list somewhere after #include<list>. Say Jun 27, 2021 · In order to find middle element of linked list in one pass, you need to maintain two pointers, one increment at each node while other increments after two nodes at a time. But in many common cases LinkedList hinders performance. (pay careful attention to how the node-to-be-freed (e. Method 1: Traverse the whole linked list and count the no . next unalloc (temp) End while End The problems use the C language syntax, so its pointer syntax. Linked lists are useful to study for two structure which you may want to use in real weaknesses of linked lists will give you an and code issues which are useful to thinking Somewhat less obviously, linked lists are great may never use a linked list in a real program, Linked list problems are a nice combination Traditionally, linked lists have been the practice to really understand pointers. 2. Yes basically the teacher showed how to create Linked Lists without the head node and to write functions using recursion, now hes showing them using this Generator Node, he says that having a node already up make it easier for adding, removing or modifying the list in some specific cases, and also that using iteration its more efficient than recursion for the memory usage. Make sure you pas the head pointer by Oct 4, 2025 · A list in C++ is a sequence container that allows you to store elements one after another. Oehm notes, is that you pass the list object to the create function. Each node contains two parts: data and references to the next and previous nodes. Mar 11, 2013 · The function Create_List (node *curr) needs some arguments. This makes it easier to keep track of the previous and next elements. Btw all those Introduction Linked lists are the best and simplest example of a dynamic data structure that uses pointers for its implementation. Jan 15, 2024 · Code in C #include <stdio. Here’s the comparison of Linked List vs Arrays Linked List: Data Structure: Non-contiguous Memory Allocation: Typically allocated one by one to Feb 19, 2025 · The idea is to handle the modification of a singly linked list by reversing its second half to allow traversal in both directions. For example, if the given linked list is 1->2->3->4->5 then the output should be 3. Below is the implementation of Sep 25, 2015 · Required knowledge Basic C programming, Functions, Singly Linked List, Dynamic memory allocation Algorithm to delete all nodes of Singly Linked List Algorithm to delete all nodes of a Singly Linked List %%Input : head node of the linked list Begin: While (head != NULL) do temp ← head head ← head. The data attribute is used to store the data in the node. 12. A doubly linked list is a list that has two references, one to the next node and another to previous node. Python linked lists are linear data structures, powerful for dynamic data management. Jul 31, 2023 · A doubly linked list is a type of linked list in which each node consists of three attributes: data, next, and previous. empty function) for the interface. Sep 26, 2015 · Write a C program to create a singly linked list of n nodes and reverse the order of nodes of the given linked list. You must also be familiar with dynamic memory allocation and structures. A cycle exists if, while traversing the list through next pointers, you encounter a node that has already been visited instead of eventually reaching nullptr. Finally, use a recursive traversal function to print the data of each node in the list. The malloc function takes in the size of the memory space we want to allocate, and returns a pointer to the memory space. For example, if the given Linked List is 5->10->15->20->25 and 30 is to be inserted, then the Linked List becomes 5->10->15->20->25->30. Do not use a loop in either operation. Did your code compile? What you should do is take a node in main which will store location of first node of the linked list. Apr 20, 2016 · Number one, who still uses linked lists (supporting opinion); Two, finding the middle node is an arbitrary, academic exercise with no value in real-life scenarios; Three, if I really needed to know the middle node, my linked list would expose a node count. Mar 31, 2013 · That depends on how you manage your linked list. I will explain step by step process to create and traverse a linked list of n nodes and display its elements. It is also easier to read: insert record into list according to criteria. There are many functions available and the following program shows a few of them: Explore how Linked Lists work in C with hands-on examples. Below is the implementation of above Feb 2, 2024 · It means that whenever we call the malloc() function, we must call the corresponding free() function at some point to release the memory. Write a member function to reverse a singly linked list using only one pass through the list. Linked Lists vs Arrays The easiest way to understand linked lists is perhaps by comparing linked lists with arrays. Unlike arrays or lists, it does not use contiguous memory. Linked List Node Representation: A node is an object which contains two fields, one stores data, and List Lists are sequence containers that allow constant time insert and erase operations anywhere within the sequence, and iteration in both directions. Essentially, linked lists In the example, the first node of the list serves as a reference to the entire list. Five ways to iterate a LinkedList are: Using for loop Using while loop Using enhanced for loop Using Iterator Using forEach () method Method 1: Using For Loop So, What is a Linked List? As you probably know, a list is an ordered collection of items. Oct 25, 2025 · LinkedList is a part of the Java Collection Framework and is present in the java. It mainly allows efficient insertion and deletion operations compared to arrays. Jul 23, 2025 · Insertion sort is especially useful in sorting linked list data structures. Below is an example of a linked list with four nodes and each node contains character data and a link to another node. Follow the steps below to solve the problem: 1. Mar 27, 2024 · Introduction There are many such operations where we need to modify the head pointer of a linked list to solve linked list-related problems. It implements a classic linked list. You are not passing any arguments from main (). Like arrays, it is also used to implement other data structures like stack, queue and deque. The first node is a special node named Head which stores the address of the first element. We also want to keep track of the current size of our List. This part works. Maintains Insertion Order: Elements are stored in Aug 30, 2025 · The idea is to reverse the linked list by changing the direction of links using three pointers: prev, curr, and next. Can use the cast-to-void ((void)param) trick to silence the compiler complaining about unused parameters or add -Wno-unused-parameter to the Makefile. I want to pass multiple values as a comma separated list to a function and accepting that list into an array variable. I could figur In this tutorial, we have introduced you to C linked list and how to implement commonly used linked list operations such as prepend, append, traverse, count, insert, remove, sort, and dispose. We would like to show you a description here but the site won’t allow us. Algorithm and steps to reverse a singly linked list. Nodes in a linked list store links to other nodes, but array elements do not need to store links to Aug 6, 2025 · At each node, print the data and recursively call the function using the next pointer until the node becomes NULL. If there are even nodes, then there would be two middle nodes, we need to print the second middle element. rzsvb agfkzx ozq smsse eln yluiyk avdb nrgdm syqck vbj nloij rhak nrldp hli fzmzz