FAQ: Build your own Mini-Blockchain! - Adding Blocks to the Chain Securely

Frequently Asked Questions Python FAQ
1

Community%20FAQs%20on%20Codecademy%20Exercises
Community%20FAQs%20on%20Codecademy%20Exercises1000×208 141 KB

This community-built FAQ covers the “Adding Blocks to the Chain Securely” exercise from the lesson “Build your own Mini-Blockchain!”.

Paths and Courses
This exercise can be found in the following Codecademy content:

Introduction to Blockchain

FAQs on the exercise Adding Blocks to the Chain Securely

There are currently no frequently asked questions associated with this exercise – that’s where you come in! You can contribute to this section by offering your own questions, answers, or clarifications on this exercise. Ask or answer a question by clicking reply (reply) below.

If you’ve had an “aha” moment about the concepts, formatting, syntax, or anything else with this exercise, consider sharing those insights! Teaching others and answering their questions is one of the best ways to learn and stay sharp.

Join the Discussion. Help a fellow learner on their journey.

Ask or answer a question about this exercise by clicking reply (reply) below!

Agree with a comment or answer? Like (like) to up-vote the contribution!

Need broader help or resources? Head here.

Looking for motivation to keep learning? Join our wider discussions.

Learn more about how to use this guide.

Found a bug? Report it!

Have a question about your account or billing? Reach out to our customer support team!

None of the above? Find out where to ask other questions here!

2

def add_block(self, transactions):
previous_hash = (self.chain[len(self.chain)-1]).hash
new_block = Block(transactions, previous_hash)
new_block.generate_hash()
proof = self.proof_of_work(new_block)
self.chain.append(new_block)
return proof, new_block

we use this proof_of_work function to add zeros as per the difficulty level but we do not see any use of it when we output the whole program , i do know why we want pow and also understood this function

def proof_of_work(self,block, difficulty=2):
proof = block.generate_hash()
while proof[:difficulty] != ‘0’*difficulty:
block.nonce += 1
proof = block.generate_hash()
block.nonce = 0
return proof

but still i dont see its significant in our final output however the add_block returns proof and new_node still we get to see only new_node its hash value and previous hash value in the final output. So why did we created such pow for this exercise

1 Like
3

You can display the proofs for your blocks in the final exercise like this. The proofs will be at the top of your output:

local_blockchain = Blockchain()

proof_1, block_1 = local_blockchain.add_block(block_one_transactions)
proof_2, block_2 = local_blockchain.add_block(block_two_transactions)
proof_3, block_3 = local_blockchain.add_block(block_three_transactions)

print(“Proof for Block 1:”, proof_1)
print(“Proof for Block 2:”, proof_2)
print(“Proof for Block 3:”, proof_3)
print(“”)

local_blockchain.print_blocks()
local_blockchain.validate_chain()