Transaction confirmation handling in Blockchain / Solidity - Step-by-Step Execution

Concept Flow - Transaction confirmation handling

Send Transaction

↓

Wait for Mining

↓

Check Confirmation Count

↓

Confirm

This flow shows sending a transaction, waiting for it to be mined, then checking if it has enough confirmations to be considered final.

Execution Sample

Blockchain / Solidity

tx_hash = send_transaction(tx)
confirmations = 0
while confirmations < 3:
    confirmations = get_confirmations(tx_hash)
    sleep(10)
print(f"Transaction confirmed with {confirmations} blocks")

This code sends a transaction and waits until it has at least 3 confirmations before proceeding.

Execution Table

Step	Action	Confirmations	Condition (confirmations < 3)	Next Step
1	Send transaction, get tx_hash	0	True	Wait and check confirmations
2	Check confirmations	1	True	Wait more blocks
3	Check confirmations	2	True	Wait more blocks
4	Check confirmations	3	False	Print confirmation message
5	Print confirmation message	3	N/A	End

💡 Confirmations reached 3, condition is false, loop ends.

Variable Tracker

Variable	Start	After Step 1	After Step 2	After Step 3	After Step 4	Final
tx_hash	None	0xabc123	0xabc123	0xabc123	0xabc123	0xabc123
confirmations	0	0	1	2	3	3

Key Moments - 3 Insights

Why do we check confirmations in a loop instead of once?

Because the transaction needs multiple blocks to be mined on top to be secure. The loop (see execution_table rows 2-4) waits until confirmations reach the required number.

What happens if confirmations never increase?

The loop keeps waiting (rows 2-4). In real code, you would add a timeout or error handling to avoid waiting forever.

Why do we print confirmation after the loop ends?

Because the loop ends only when confirmations >= 3 (row 4), so printing then means the transaction is safely confirmed.

Visual Quiz - 3 Questions

Look at the execution_table, what is the value of confirmations at Step 3?

A 0

B 2

C 1

D 3

💡 Hint

Check the 'Confirmations' column at Step 3 in the execution_table.

At which step does the condition 'confirmations < 3' become false?

A Step 4

B Step 3

C Step 2

D Step 5

💡 Hint

Look at the 'Condition' column in the execution_table to find when it changes to False.

If we change the required confirmations to 2, at which step would the loop end?

A Step 2

B Step 4

C Step 3

D Step 5

💡 Hint

Refer to the 'Confirmations' and 'Condition' columns in the execution_table to see when condition becomes false for 2 confirmations.

Concept Snapshot

Transaction confirmation handling:
- Send transaction and get tx_hash
- Loop: check confirmations count
- Wait until confirmations >= required number
- Confirmations mean blocks mined on top
- Print or proceed after enough confirmations

Full Transcript

This visual execution shows how a blockchain transaction is confirmed. First, the transaction is sent and a transaction hash is received. Then, the program checks how many confirmations the transaction has by counting blocks mined on top. It loops, waiting and checking repeatedly until the confirmations reach the required number (3 in this example). Once confirmed, it prints a message. Variables like tx_hash and confirmations update step-by-step. Key points include why we wait for multiple confirmations for security, and that the loop ends only when confirmations are enough. The quiz questions help check understanding of confirmation counts and loop behavior.