Write and test a contract

Build a small Solidity contract in Remix, then deploy it with MetaMask on Tavchain Testnet. You do not need a node, terminal or private-key export for this browser workflow.

Before you begin

Use a desktop browser with MetaMask installed. Add Tavchain Testnet and obtain Test TAV. Keep your seed phrase and private key inside your wallet.

Create Greeter

Open Remix’s file explorer, create Greeter.sol at the root of your workspace and paste the example below. It starts with Hello, lets anyone change the greeting and emits an event for each change. It is a demonstration contract with no ownership restriction.

Greeter.sol

pragma solidity 0.8.21;

contract Greeter {
    string public greeting;

    event ChangeGreeting(address from, string value);

    constructor() public {
        greeting = "Hello";
    }

    function setGreeting(string memory _greeting) public {
        greeting = _greeting;
        emit ChangeGreeting(msg.sender, _greeting);
    }

    function greet() public view returns (string memory) {
        return greeting;
    }
}

Solidity reports warnings for this example’s missing SPDX identifier and ignored constructor visibility; neither is a compilation error. This simple demonstration is not an audited application or a contract for holding funds.

Compile Greeter

In Solidity Compiler, select:

Setting	Value
Compiler	`0.8.21+commit.d9974bed`
Language	Solidity
EVM version	Shanghai
Optimization	Enabled
Runs	200

Open Advanced Configurations to find the EVM target and optimizer. Click Compile Greeter.sol, then select Greeter in the contract selector. Resolve any compilation errors before continuing. Retain the source, compiler settings, ABI and bytecode. Keep the original Standard JSON compiler input when your build produces it; it can be used for source verification. Changing the source filename can change Solidity’s metadata and full bytecode even when the executable logic is unchanged.

Continue to deployment

Follow deploy and interact to connect MetaMask, deploy once and read Hello. You can then make the optional Hello Tavchain update and verify the source. The verified Greeter example uses this source as Greeter.sol with the settings above. Use your own deployment for a predictable initial greeting. Use the compiler and EVM settings above for this example. Check compatibility before changing compiler versions or targeting a different EVM revision.

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Write and test a contract

Before you begin

Create Greeter

Compile Greeter

Continue to deployment

Before you begin

Create Greeter

Compile Greeter

Continue to deployment

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