Create and prepare a smart contract

First of all, you need to create and prepare your smart contract to work with it. To do this:

1. Install Solidity compiler by running the following command:

   npm install -g solc
   Note

   You can find the Solidity compiler description and usage here.

2. Ensure you are in dcloud_example directory, you've created on step 1 here, or create this directory, if you haven't done it yet.

3. Open a smart contract file greeter.sol, which contains the following code:

   //SPDX-License-Identifier: Unlicense
    pragma solidity ^0.8.13;
    contract Greeter {
    string private greeting;
   
    constructor() {
    	greeting = 'Hello World!';
    }
   
    function greet() public view returns (string memory) {
    	return greeting;
    }
    
    function setGreeting(string memory _greeting) public {
    	greeting = _greeting;
    }
   }

   The main actions in this code example:

   1. Declaration of a new contract variable, where the greeting variable will be stored:

      string private greeting;

   2. Declaration of contract inner variable, where the greeting variable will be stored:

      constructor() {
        greeting = 'Hello World!';
      }

      When you create a smart contract, the greeting variable is initialized with a classical Hello World! text.

   3. The greet() function returns the current greeting.

   4. The setGreeting() function replaces the current greeting with a new one.

4. Compile the given code. You will receive an .abi file:

   Run the following command in the directory, where the greeter.sol file is stored:

   1.   solcjs --bin greeter.sol

      As a result you will get a greeter_sol_Greeter.bin file.

   2. You can also find greeter_sol_Greeter.json that you will need in further steps.