ERC20

ERC20 Sepc

ERC20 is the standard for fungible tokens on Ethereum.

pragma solidity ^0.6.0;
 
interface IERC20 {
 
    function totalSupply() external view returns (uint256);
    function balanceOf(address account) external view returns (uint256);
    function allowance(address owner, address spender) external view returns (uint256);
 
    function transfer(address recipient, uint256 amount) external returns (bool);
    function approve(address spender, uint256 amount) external returns (bool);
    function transferFrom(address sender, address recipient, uint256 amount) external returns (bool);
 
 
    event Transfer(address indexed from, address indexed to, uint256 value);
    event Approval(address indexed owner, address indexed spender, uint256 value);
}

Transfer vs TransferFrom

The transfer methods is 2 party transfer:

• Sender → transfer(receiver_address, amount)

The transferFrom method is 3 part transfer:

• Sender → approve(exchange_address, amount)
• Buyer → trade on the exchange
• Exchange → transferFrom(sender_address, buyer_address, amount)