If i already have an ERC20 tokens created and has basic functionalities of a token sat at contract address A, can i start to develop a new smart contract which can make use of the ERC20 token at contract address A.

1 Answer 1


Yes. This should be no problem to implement this, as erc-20 tokens can be owned by smart contracts as well as external accounts. In general, there's no restriction on which accounts can own a token.

You can use the code below as a reference:

pragma solidity 0.4.25;

// Import OpenZeppelin's ERC20 interface defenition
import "https://github.com/OpenZeppelin/openzeppelin-solidity/contracts/token/ERC20/IERC20.sol";
import "https://github.com/OpenZeppelin/openzeppelin-solidity/contracts/token/ERC20/ERC20.sol";

// Simple ERC20 token that mints the given initialSupply to the deployer
// For testing purposes
contract MyToken is ERC20 {
    string public name = "MyToken";
    string public symbol = "MYT";
    uint256 public decimals = 18;

    constructor(uint256 _intialSupply) public {
        _mint(msg.sender, _intialSupply);

// Contract that uses any ERC20 token
contract UsingERC20 {
    IERC20 public associatedToken;

    // Constructor. Pass it the token you want this contract to work with
    constructor(IERC20 _token) public {
        associatedToken = _token;

    function doSomethingThatRequiresERC20tokens() public {
        // The key here is to use ERC20's transferFrom method.
        // For this to work, the given address has to have enough balance,
        // and it has to allow this contract to transfer tokens from their account.
        // This can be done using ERC20's approve method/

        // If transferFrom fails, the transaction reverts. So if the transaction
        // does not revert, we know that the transer succeeded.

        // Using msg.sender here, the caller of this function.
        // Could be any address you like, though.
        // This transfers 100 tokens from msg.sender to this contract.
        associatedToken.transferFrom(msg.sender, address(this), 100);

        // Ok, now the tokens are transferred successfully, let's do some cool stuff!
        emit YayIReceivedTokens(100, msg.sender, associatedToken.balanceOf(address(this)));

    event YayIReceivedTokens(uint256 amount, address fromAccount, uint256 totalBalance);
  • Thank you for the answer, say like i need to have a function in my smart contract which can receive an erc 20 token and perform an action, could you let me know any sample of how this can be achieved. I only need the function to work with that unique token and nothing else Oct 23, 2018 at 5:36
  • I Updated my answer with an example
    – Henk
    Oct 23, 2018 at 8:45
  • Thanks. I got this idea, let me try and update you Oct 23, 2018 at 17:36

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service and acknowledge you have read our privacy policy.

Not the answer you're looking for? Browse other questions tagged or ask your own question.