@xuanling11 19 August 2022 more from that month

Learning Blockchain through Python: Part 1 Blockchain is a big word and a confusing word to newbies.  A blockchain is an online public bookkeeping ledger.

It automatically registers a financial transaction from the sender to the receiver. Before we go into depth about the blockchain, let’s build a simple financial transaction from Python. Here are the thought processes: What information do you need to complete a transaction? You will need: 👉 sender’s name 👉 receiver’s name 👉 amount to transact How do you store the data with information? In Python, dictionaries are preferable for transaction data storage since it is a set of *key: value* pairs that are searchable. https://docs.python.org/3/tutorial/datastructures.html **Construction a transaction** If Alice, the sender, sent $30 to Bob, the receiver, through a transaction, here is how to construct the data: transaction1 = { ‘amount’: ‘30’, ‘sender’: ‘Alice’, ‘receiver’: ‘Bob’} More transactions You can register more transactions by repeating the above method: transaction2 = { ‘amount’: ‘200’, ‘sender’: ‘Bob’, ‘receiver’: ‘Alice’} transaction3 = { ‘amount’: ‘300’, ‘sender’: ‘Alice’, ‘receiver’: ‘Bob’ } transaction4 = { ‘amount’: ‘300’, ‘sender’: ‘Bob’, ‘receiver’: ‘Alice’ } transaction5 = { ‘amount’: ‘200’, ‘sender’: ‘Alice’, ‘receiver’: ‘Bob’ } transaction6 = { ‘amount’: ‘400’, ‘sender’: ‘Bob’, ‘receiver’: ‘Alice’ } Combine all transactions together Assume you will have six transactions total. You combine them together in one assigned variable, “*mempool*”: mempool = [transaction1, transaction2, transaction3, transaction4, transaction5, transaction6] Add one more transaction Since there is a new transaction that needs to register in the blockchain, we can add through *.append()* : my_transaction = { ‘amount’: ‘100’, ‘sender’: ‘Alice’, ‘receiver’: ‘Bob’ } mempool.append(my_transaction) Search transactions Now, you have got your ledger input through Python manually! You can search transactions whichever you want to. For instance, if you want the first 3 transactions, you can do: block_transactions = mempool[0:3] print(block_transactions) Congratulation! You got your blockchain! Although it does not automatically generate and capture transactions, you get your first blockchain at least! You can have a code below: transaction1 = { 'amount': '30', 'sender': 'Alice', 'receiver': 'Bob'} transaction2 = { 'amount': '200', 'sender': 'Bob', 'receiver': 'Alice'} transaction3 = { 'amount': '300', 'sender': 'Alice', 'receiver': 'Bob' } transaction4 = { 'amount': '300', 'sender': 'Bob', 'receiver': 'Alice' } transaction5 = { 'amount': '200', 'sender': 'Alice', 'receiver': 'Bob' } transaction6 = { 'amount': '400', 'sender': 'Bob', 'receiver': 'Alice' } mempool = [transaction1, transaction2, transaction3, transaction4, transaction5, transaction6] #1 add a new transaction my_transaction = { 'amount': '100', 'sender': 'Alice', 'receiver': 'Bob' } #2 add new transaction to the existing one mempool.append(my_transaction) #test print #print(mempool) #3 create a new list of addtional three new transactions block_transactions = mempool[0:3] print(block_transactions)