Transaction confirmation handling in Blockchain / Solidity - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to check if a transaction is confirmed.

Blockchain / Solidity

if transaction.status == [1]:
    print("Transaction confirmed")

Drag options to blanks, or click blank then click option'

A"confirmed"

B"pending"

C"failed"

D"unknown"

Attempts:

3 left

💡 Hint

Common Mistakes

Using "pending" instead of "confirmed".

Checking for "failed" status.

The transaction status must be "confirmed" to indicate it is successfully processed.

2fill in blank

medium

Complete the code to wait for 3 confirmations before proceeding.

Blockchain / Solidity

while transaction.confirmations < [1]:
    wait_for_new_block()

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A0

B1

C6

D3

Attempts:

3 left

💡 Hint

Common Mistakes

Using 1 confirmation which might be unsafe.

Using 0 which means no wait.

Waiting for 3 confirmations is a common practice to ensure transaction finality.

3fill in blank

hard

Fix the error in the code to correctly check transaction finality.

Blockchain / Solidity

if transaction.confirmations [1] 3:
    print("Transaction is final")

Drag options to blanks, or click blank then click option'

A>=

B==

C<

D!=

Attempts:

3 left

💡 Hint

Common Mistakes

Using '<' which checks for fewer confirmations.

Using '==' which is too strict.

Transaction is final when confirmations are greater than or equal to 3.

4fill in blank

hard

Fill both blanks to create a dictionary of transaction IDs with their confirmation counts greater than 2.

Blockchain / Solidity

confirmed_txs = {tx.id: tx[1] for tx in transactions if tx.confirmations [2] 2}

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A.confirmations

B>

C>=

D.status

Attempts:

3 left

💡 Hint

Common Mistakes

Using '.status' instead of '.confirmations'.

Using '>=' instead of '>'.

We want the confirmation count for each transaction and only those with more than 2 confirmations.

5fill in blank

hard

Fill all three blanks to filter transactions with status 'confirmed' and confirmations at least 3, then map their IDs to confirmation counts.

Blockchain / Solidity

final_txs = {tx[1]: tx[2] for tx in transactions if tx.status == [3] and tx.confirmations >= 3}

Drag options to blanks, or click blank then click option'

A.id

B.confirmations

C"confirmed"

D"pending"

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'pending' instead of 'confirmed' for status.

Mixing up keys and values in the dictionary.

This code creates a dictionary with transaction IDs as keys and their confirmation counts as values, only for confirmed transactions with at least 3 confirmations.