Introduction to Smart Contracts Pt2

Continuing from the first post, we have gone over the examples of smart contracts and what they essentially look like with an explanation. Now I am going to continue and get more into detail. Here is where we left off, with this subcurrency example: // SPDX-License-Identifier: GPL-3.0 pragma solidity ^0.8.4; contract Coin { // The keyword "public" makes variables // accessible from other contracts address public minter; mapping (address => uint) public balances; // Events allow clients to react to specific // contract changes you declare event Sent(address from, address to, uint amount); // Constructor code is only run when the contract // is created constructor() { minter = msg.sender; } // Sends an amount of newly created coins to an address // Can only be called by the contract creator function mint(address receiver, uint amount) public { require(msg.sender == minter); balances[receiver] += amount; } // Errors allow you to provide information about // why an operation failed. They are returned // to the caller of the function. error InsufficientBalance(uint requested, uint available); // Sends an amount of existing coins // from any caller to an address function send(address receiver, uint amount) public { if (amount > balances[msg.sender]) revert InsufficientBalance({ requested: amount, available: balances[msg.sender] }); balances[msg.sender] -= amount; balances[receiver] += amount; emit Sent(msg.sender, receiver, amount); } } address is a type where the variable will take in an address type. Its only for an address and no operations done. It can store addresses of contracts and half of a key pair belonging to any external accounts.

Feb 16, 2025 - 09:56

Continuing from the first post, we have gone over the examples of smart contracts and what they essentially look like with an explanation. Now I am going to continue and get more into detail.

Here is where we left off, with this subcurrency example:

// SPDX-License-Identifier: GPL-3.0
pragma solidity ^0.8.4;

contract Coin {
    // The keyword "public" makes variables
    // accessible from other contracts
    address public minter;
    mapping (address => uint) public balances;

    // Events allow clients to react to specific
    // contract changes you declare
    event Sent(address from, address to, uint amount);

    // Constructor code is only run when the contract
    // is created
    constructor() {
        minter = msg.sender;
    }

    // Sends an amount of newly created coins to an address
    // Can only be called by the contract creator
    function mint(address receiver, uint amount) public {
        require(msg.sender == minter);
        balances[receiver] += amount;
    }

    // Errors allow you to provide information about
    // why an operation failed. They are returned
    // to the caller of the function.
    error InsufficientBalance(uint requested, uint available);

    // Sends an amount of existing coins
    // from any caller to an address
    function send(address receiver, uint amount) public {
        if (amount > balances[msg.sender])
            revert InsufficientBalance({
                requested: amount,
                available: balances[msg.sender]
            });

        balances[msg.sender] -= amount;
        balances[receiver] += amount;
        emit Sent(msg.sender, receiver, amount);
    }
}

address is a type where the variable will take in an address type. Its only for an address and no operations done. It can store addresses of contracts and half of a key pair belonging to any external accounts.