Ethereum networks (mainnet, testnet) in Blockchain / Solidity - Step-by-Step Execution

Concept Flow - Ethereum networks (mainnet, testnet)

Start: Choose Network

↓

Use Testnet

Yes↓

Use Mainnet

↓

Deploy/Interact with Contracts

↓

Transactions Confirmed

↓

End

You pick a network: mainnet for real money or testnet for practice. Then you deploy or interact with contracts and wait for confirmations.

Execution Sample

Blockchain / Solidity

network = "testnet"
if network == "mainnet":
    print("Using real Ethereum network")
else:
    print("Using test network for practice")

This code chooses between mainnet and testnet and prints which network is used.

Execution Table

Step	Variable 'network'	Condition 'network == "mainnet"'	Branch Taken	Output
1	"testnet"	False	Else branch	"Using test network for practice"
2	-	-	-	Program ends

💡 Condition is false because network is 'testnet', so else branch runs and program ends.

Variable Tracker

Variable	Start	After Step 1	Final
network	undefined	"testnet"	"testnet"

Key Moments - 2 Insights

Why does the program print 'Using test network for practice' instead of 'Using real Ethereum network'?

Because the variable 'network' is set to 'testnet', the condition 'network == "mainnet"' is false (see execution_table step 1), so the else branch runs.

What is the difference between mainnet and testnet?

Mainnet is the real Ethereum network where real money is used. Testnet is a practice network with fake money to test code safely.

Visual Quiz - 3 Questions

Look at the execution table, what is the value of 'network' at Step 1?

A "testnet"

B undefined

C "mainnet"

D "unknown"

💡 Hint

Check the 'Variable network' column in execution_table at Step 1.

At which step does the program decide to run the else branch?

A Step 2

B Program never runs else branch

C Step 1

D Before Step 1

💡 Hint

Look at the 'Branch Taken' column in execution_table.

If 'network' was set to 'mainnet', what would the output be?

A "Using test network for practice"

B "Using real Ethereum network"

C No output

D Error

💡 Hint

Think about the condition 'network == "mainnet"' and which branch runs.

Concept Snapshot

Ethereum networks:
- Mainnet: real Ethereum, real money
- Testnet: practice network, fake money
- Use 'if' to choose network
- Deploy/test contracts safely on testnet
- Switch to mainnet for real transactions

Full Transcript

This visual trace shows how a program chooses between Ethereum mainnet and testnet. The variable 'network' is set to 'testnet'. The program checks if 'network' equals 'mainnet'. Since it does not, it runs the else branch and prints 'Using test network for practice'. Mainnet is the real Ethereum network with real money. Testnet is a safe practice network with fake money. This helps developers test their code without risking real funds. The execution table tracks each step, showing variable values, conditions, branches, and output. The variable tracker shows how 'network' stays 'testnet'. Key moments clarify why the else branch runs and the difference between mainnet and testnet. The quiz asks about variable values and program flow to reinforce understanding.