Tutorial: Create an ERC-20 Token

ERC-20 Tokens are the types of tokens used in most initial coin offerings (ICOs). They are a standard type of token which is based on Ethereum, and they’re surprisingly easy to create.

To help you quickly create an ERC-20 token, I have provided the following open source code below which you can modify and use for your own purposes. (View instructional video at: https://youtu.be/b3kzi4UVdCk)

NOTE: Remix.Ethereum.Org has made some adjustments in the latest versions of the Solidity compilers and as a result you may come across an error when you compile the code. To get around this issue, select an earlier version of the compiler, preferably 0.4.24+commit.e67f0147.Emscripten.clang or earlier.

Create an ERC-20 Token Sample Source Code

Code starts below the following line.

pragma solidity ^0.5.0;

// —————————————————————————-
// ERC Token Standard #20 Interface
//
// —————————————————————————-
contract ERC20Interface {
function totalSupply() public view returns (uint);
function balanceOf(address tokenOwner) public view returns (uint balance);
function allowance(address tokenOwner, address spender) public view returns (uint remaining);
function transfer(address to, uint tokens) public returns (bool success);
function approve(address spender, uint tokens) public returns (bool success);
function transferFrom(address from, address to, uint tokens) public returns (bool success);

event Transfer(address indexed from, address indexed to, uint tokens);
event Approval(address indexed tokenOwner, address indexed spender, uint tokens);

}

// —————————————————————————-
// Safe Math Library
// —————————————————————————-
contract SafeMath {
function safeAdd(uint a, uint b) public pure returns (uint c) {
c = a + b;
require(c >= a);
}
function safeSub(uint a, uint b) public pure returns (uint c) {
require(b <= a); c = a – b; } function safeMul(uint a, uint b) public pure returns (uint c) { c = a * b; require(a == 0 || c / a == b); } function safeDiv(uint a, uint b) public pure returns (uint c) { require(b > 0);
c = a / b;
}
}

contract ERC20SeedCode is ERC20Interface, SafeMath {
string public name;
string public symbol;
uint8 public decimals; // 18 decimals is the strongly suggested default, avoid changing it

uint256 public _totalSupply;

mapping(address => uint) balances;
mapping(address => mapping(address => uint)) allowed;

/**
 * Constrctor function
 *
 * Initializes contract with initial supply tokens to the creator of the contract
 */
constructor() public {
    name = "NAME";// Set the name for display purposes

    symbol = "SYMBOL";// Set the symbol for display purposes
    decimals = 0;// Amount of decimals for display purposes
    _totalSupply = 5000000000000;// Update total supply (100000 for example)

    balances[msg.sender] = _totalSupply;
    emit Transfer(address(0), msg.sender, _totalSupply);
}

function totalSupply() public view returns (uint) {
    return _totalSupply  - balances[address(0)];
}

function balanceOf(address tokenOwner) public view returns (uint balance) {
    return balances[tokenOwner];
}

function allowance(address tokenOwner, address spender) public view returns (uint remaining) {
    return allowed[tokenOwner][spender];
}

function approve(address spender, uint tokens) public returns (bool success) {
    allowed[msg.sender][spender] = tokens;
    emit Approval(msg.sender, spender, tokens);
    return true;
}

function transfer(address to, uint tokens) public returns (bool success) {
    balances[msg.sender] = safeSub(balances[msg.sender], tokens);
    balances[to] = safeAdd(balances[to], tokens);
    emit Transfer(msg.sender, to, tokens);
    return true;
}

function transferFrom(address from, address to, uint tokens) public returns (bool success) {
    balances[from] = safeSub(balances[from], tokens);
    allowed[from][msg.sender] = safeSub(allowed[from][msg.sender], tokens);
    balances[to] = safeAdd(balances[to], tokens);
    emit Transfer(from, to, tokens);
    return true;
}

}