Python Linked List: Set a new value of an item in a singly linked list using index value

Last update on April 23 2025 12:56:41 (UTC/GMT +8 hours)

5. Set Value by Index in Singly Linked List

Write a Python program to set a new value of an item in a singly linked list using index value.

Sample Solution:

Python Code:

class Node:
    # Singly linked node
    def __init__(self, data=None):
        self.data = data
        self.next = None
class singly_linked_list:
    def __init__(self):
        # Createe an empty list
        self.tail = None
        self.head = None
        self.count = 0

    def append_item(self, data):
        #Append items on the list
        node = Node(data)
        if self.head:
            self.head.next = node
            self.head = node
        else:
            self.tail = node
            self.head = node
        self.count += 1
    
    def __getitem__(self, index):
        if index > self.count - 1:
            return "Index out of range"
        current_val = self.tail
        for n in range(index):
            current_val = current_val.next
        return current_val.data
    
    def __setitem__(self, index, value):
        if index > self.count - 1:
            raise Exception("Index out of range.")
        current = self.tail
        for n in range(index):
            current = current.next
        current.data = value

items = singly_linked_list()
items.append_item('PHP')
items.append_item('Python')
items.append_item('C#')
items.append_item('C++')
items.append_item('Java')

print("Modify items by index:")
items[1] = "SQL"
print("New value: ",items[1])
items[4] = "Perl"
print("New value: ",items[4])

Sample Output:

Modify items by index:
New value:  SQL
New value:  Perl

Flowchart:

For more Practice: Solve these Related Problems:

Write a Python program to update the value of a node at a given index in a singly linked list and then display the updated list.
Write a Python script to implement a function that replaces a node's value at a specified index and prints the entire list afterward.
Write a Python program to recursively set a new value at a specific index in a singly linked list and verify the change by iterating through the list.
Write a Python function to update a node in a singly linked list based on index and then compare the updated list with a copy of the original.

Go to:

Previous: Write a Python program to access a specific item in a singly linked list using index value.
Next: Write a Python program to delete the first item from a singly linked list.

Python Code Editor:

Contribute your code and comments through Disqus.