School of Rich Programmers: 7495.org

Web3 Educational Lab: Interacting with a Token Vendor Smart Contract

This hands-on exercise demonstrates how smart contracts autonomously process state changes, calculate exchange rates, and execute multi-step transfers within a single transaction.

🔎 Concept Overview

You are interacting with a Token Vendor Contract. When you send native cryptocurrency (such as ETH or BNB) to the contract address, the contract automatically triggers a reverse transfer, sending back custom laboratory tokens at a fixed rate of 1:1,000 (e.g., 0.001 ETH = 1 Token / 1 BTC Test token credit equivalent).

Thanks to multi-chain deterministic deployment, both the Vendor and the Token share the exact same addresses across all supported networks.

🛠 Technical Parameters & Deployment Addresses

• Supported Networks:

✅ Ethereum (Mainnet & Holesky Testnet)

✅ Binance Smart Chain (Mainnet & Testnet)

• Vendor Contract Address (To): 0x52fa8Ed3F4e719728d8db900E687D8f08435A98F

• Returned Token Contract Address: 0xB300F9D0A1D53E81be181495B324C65C839422e1

• Recommended Gas Limit: 66666 (Crucial: Standard peer-to-peer transfers use 21,000 gas. However, because this contract executes internal logic and triggers a secondary token transfer, it requires more computational power. Any unused gas will be automatically refunded to your wallet).

🚀 Step-by-Step Execution Guide

Step 1: Network & Wallet Setup

Ensure your Web3 wallet (e.g., MetaMask) is connected to your preferred network. For safety and testing purposes, we highly recommend starting with test networks (Ethereum Holesky or BSC Testnet) using free faucet coins.

Step 2: Import the Custom Token to Your Wallet

Before sending funds, add the token to your wallet interface so you can see your new balance instantly:

1. Open your wallet and scroll down to "Import tokens" or "Custom Token".

2. Paste the Token Address: 0xB300F9D0A1D53E81be181495B324C65C839422e1

3. The token symbol and decimals should autofill. Confirm and click Add.

Step 3: Initiating a Manual Transfer (The Exchange)

1. In your wallet, click Send.

2. Paste the Vendor Contract address in the recipient field: 0x52fa8Ed3F4e719728d8db900E687D8f08435A98F

3. Enter a micro-amount to safely test the contract mechanics (e.g., 0.001 or 0.01).

Step 4: Adjusting Gas Limits (Advanced Settings)

Before confirming the transaction, you must manually adjust the transaction parameters to avoid an "Out of Gas" error:

1. On the wallet confirmation screen, look for Gas Market / Advanced Settings (often hidden behind a gear or "Market" icon).

2. Locate the Gas Limit field (do not confuse this with Gas Price / Base Fee).

3. Change the value to 66666.

4. Confirm and broadcast the transaction to the blockchain.

Step 5: Auditing the Blockchain Explorer

Once the transaction is confirmed, you can verify its complete architecture by pasting your wallet address or the Vendor address into a blockchain explorer (Etherscan, Holesky Etherscan, or BscScan).

In the transaction details, you will observe the precise atomic nature of smart contracts:

• From: Your Address ➡️ To: Vendor Contract (Your native crypto transfer)

• From: Vendor Contract ➡️ To: Your Address (The automated 1:1,000 token delivery)

Consider the following examples:

Wallet-Online.htm

1. RPC from the List of Chains

2. Vendor Contract Address (To): 0x52fa8Ed3F4e719728d8db900E687D8f08435A98F

3. Custom Gas Limit: 66666

Result:

Binance Smart Chain (Testnet):
https://testnet.bscscan.com/txs?a=0x52fa8ed3f4e719728d8db900e687d8f08435a98f&f=3

Binance Smart Chain (Mainnet):
https://bscscan.com/txs?a=0x52fa8ed3f4e719728d8db900e687d8f08435a98f&f=3

Ethereum (Mainnet):
https://etherscan.io/txs?a=0x52fa8ed3f4e719728d8db900e687d8f08435a98f&f=3

1 BNB = 1000 BTC Test
0.1 BNB = 100 BTC Test
0.01 BNB = 10 BTC Test
0.001 BNB = 1 BTC Test

Coin: BTC Test (BTC)
Coin: ETH Test (ETH)
Coin: BNB Test (BNB)