ERC20 standard API

ERC20 is the token standard API that defines functions so that they can access the status of the token, the token's details, and account balances. You can find the original EIP of the ERC20 standard on the GitHub repository of the Ethereum project: https://github.com/ethereum/EIPs/blob/master/EIPS/eip-20.md.

The following is the standard API interface defined in Solidity:

interface ERC20FullInterface {
    //Below are the OPTIONAL functions of API
    function name() external view returns (string);

    function symbol() external view returns (string);

    function decimals() external view returns (uint8);

    //Below are the functions an implementation MUST have
    function transfer(address to, uint256 value) 
      external returns (bool);

    function approve(address spender, uint256 value) 
      external returns (bool);

    function transferFrom(address from...