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Created using remix-ide: Realtime Ethereum Contract Compiler and Runtime. Load this file by pasting this gists URL or ID at
// SPDX-License-Identifier: GPL-3.0
pragma solidity >=0.7.0 <0.9.0;
contract myToken {
string public constant name = "Tokenomics";
string public constant symbol = "TOK";
uint8 public constant decimals = 18; // 18 is the most common number of decimal places
uint _totalSupply;
// Balances for each account stored using a mapping
mapping(address => uint256) balances;
// Owner of the account approves the allowance of another account
// Create an allowance mapping
// The first key is the owner of the tokens
// In the 2nd mapping, its says who can spend on your behalf, and how many
// So, we are creating a mapping, where the kep is an address,
// The value is further a mapping of address to amount
mapping(address => mapping (address => uint256)) allowance;
event Transfer(address indexed from, address indexed to, uint tokens);
event Approval(address indexed tokenOwner, address indexed spender, uint tokens);
// Called automatically when contract is initiated
// Sets to total initial _totalSupply, as per the input argument
// Also gives the initial supply to msg.sender...who creates the contract
constructor(uint amount) {
_totalSupply = amount;
balances[msg.sender] = amount;
// Returns the total supply of tokens
function totalSupply() public view returns (uint256) {
return _totalSupply;
// Transfer the balance from owner's account to another account
// Decreases the balance of "from" account
// Increases the balance of "to" account
// Emits Transfer event
function transfer(address to, uint tokens) public returns (bool success) {
if(tokens < 1){
revert("Not enough Ether provided.");
require(tokens <= balances[msg.sender]);
balances[msg.sender] = balances[msg.sender] - tokens;
balances[to] = balances[to] + tokens;
emit Transfer(msg.sender, to, tokens);
return true;
// Get the token balance for account `tokenOwner`
// Anyone can query and find the balance of an address
function balanceOf(address tokenOwner) public view returns (uint) {
return balances[tokenOwner];
// Send amount of tokens from address `from` to address `to`
// The transferFrom method is used to allow contracts to spend
// tokens on your behalf
// Decreases the balance of "from" account
// Decreases the allowance of "msg.sender"
// Increases the balance of "to" account
// Emits Transfer event
function transferFrom(address from, address to, uint tokens) public returns (bool success) {
balances[from] = balances[from] - tokens;
allowance[from][msg.sender] = allowance[from][msg.sender] - tokens;
balances[to] = balances[to] + tokens;
emit Transfer(from, to, tokens);
return true;
// Approves the `spender` to withdraw from your account, multiple times, up to the `tokens` amount.
// So the msg.sender is approving the spender to spend these many tokens
// from msg.sender's account
// Setting up allowance mapping accordingly
// Emits approval event
function approve(address spender, uint tokens) public returns (bool success) {
allowance[msg.sender][spender] = tokens;
emit Approval(msg.sender, spender, tokens);
return true;
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shoupn commented Feb 5, 2022

example of a token using ERC-20 standard.

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