Solidity Tutorial: ERC20 token transfers (transfer, transferFrom, approve)

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With ERC20 tokens, there are 2 APIs to transfer tokens:
- transfer() (simple transfers)
- transferFrom() (delegated transfer)
For transfer(), there are 3 steps:
1. Import the ERC20 token
2. Import the address of the token
3. Call transfer()
For transfer(), there are 4 steps:
1. Import the ERC20 token
2. Import the address of the token
3. Call approve()
4. Call transferFrom()
Watch this video to understand how this all fits together, so that you learn how to transfer ERC20 tokens in Solidity.
WATCH Whole Solidity tutorial series: • Solidity Tutorial: Int...

[@rickhoro]

All the other videos are great to this point. Sorry, but I find this one to be confusing.

[@nolestock4291]

love the videos. small critique: i would have preferred to see you deploy everything and interact with the contract's through their interface. there's still a gap in my understanding.

[@andrianski12]

Good job, keep going

[@MotherCoin]

Thank you

[@sandeepbhattacharya8158]

What about security and sanity checks is openzappalin contracts taking care of it or we should implement our own like checking balance first null or empty address require from owner etc?

[@Artixou]

Hey Julian, keep posting these - very useful.

[@malkiattal4297]

i wish you did this amazing tutorial in french bro, still very clear and interresting, thank you !!

[@EatTheBlocks]

Glad you liked it!

[@aga080]

Can you please make a video on the multiTransfer function?

[@Mrpjm200]

Should the line: transferToken.transferFrom(recipient, amount); have been put in a separate function, which can be called by the approved contract (e.g. not in the Owner contract)?

[@drakegao816]

Maybe I missed something. Why can you pass the token as an argument into the TransferToken contract at line 28? Thanks.

[@aatkaKhan]

Hey Julian, great tutorial! Just want to know if there is another simple way to use these transfer functions in our smart contract.

[@drabbani90]

hi julian , in my contract i have did the same thing the approve and transfer from function , but when i do the transfer from function with the price for example i want to send 100 Tokens it always give gas estimation errored when i do the value as '0' then it aproves the transaction but no erc tokens are transfered can you please tell me any solution for that

[@amarachiugwu_]

Nice video Julian, does this also work for BEP20 Tokens?

[@EatTheBlocks]

Yes, it's the same

[@consciousnova8337]

how did you declare the 'token' variable? When I try to do 'Token token = Token(_address_)' it gives me an error 'Identifier not found or not unique' I'm doing compiler ^0.8.0

[@azharkhanyt]

Can you help me Transfer my erc20 token to on the exchanger?

[@anyasiuche5617]

Hey Julian thanks for this videos..but why cant i deploy the token.sol contract? remix keeps showing an error alert < _This contract may be abstract, not implement an abstract parent's methods completely or not invoke an inherited contract's constructor correctly_ >

[@anyasiuche5617]

lolz..i was able to solve it by watching your next video in the series by calling the parent constructor >> constructor() ERC20('Token', 'TOK'){} then i removed the _abstract_ keyword from token contract.

[@wasifkarim1698]

Can't it be deployed like that of sending ether videos ? please , tell me why I am able to deploy it ? Token.sol is not being compiled. It gives error. Someone please help!

[@1223whiteguy]

Your accent makes me believe in love, merci

[@EatTheBlocks]

haha!

[@hamza-325]

Yeah, I usually get mad when I hear the strong french accent in the tutorials done by some French people and I can't focus because of it, but his accent is an exception, it is really great!

[@anthonynolanjannotta4688]

How can i interact with an ERC20 token if i don't have the solidity file? Is there another way to import it into my contract? Thanks!

[@EatTheBlocks]

You just need the interface

[@gamersvideoclips8309]

Y dont you show its working

[@victordanu5022]

is it the same for bep20?

[@EatTheBlocks]

yes

[@manishapadole4173]

this is not working please share it with testnet deployment and transfer from function

[@Yasinaktimur]

can you share your codes as gist

[@EatTheBlocks]

good idea, I ll think about it. In the meantime, you can register as a free member of EatTheBlocks at pro.eattheblocks.com for the source code of many tutorials

[@alexmelka5324]

why only two arguments line 20 ?

[@EatTheBlocks]

I will check

[@subujekupadupa]

@@EatTheBlocks have you ever checked it?

[@repzo5551]

Because it's msg.sender that is passed as a parameter on line 22. If you wanted to change that, then yes, an additionnal argument would be needed

[@yadusolparterre]

What is a TransferToken? Why not call it Token? Other tokens cannot be transferred? You show the ERC20 implementation but then you import a Token.sol... what is the connection between the two? And why call a contract Owner? The contract owns another contract? This is incredibly confusing. You create more questions than you answer

[@satadalchakravarty3911]

who is going to show the deployment ????

[@alexirabor]

Your videos are good, but you never run your programs. You just code and stop.

[@waleednaseem8571]

is anyone here to guide me ?

[@jorgerozenberg4519]

I don't understand which is the address of the token

[@su4per2star0]

line 16 and 29 but he's just using a random address... if you go back one video in the playlist he shows you how to write a function to set the real address kzbin.info/www/bejne/j6m4aWqlabpon9k

[@alfonsopayra]

this video is not clear at all, sorry mate but i will push not like for this one

[@Shack318]

This is showing a scammer how to steal or take over a token scam. Why would youtube let this guy make a video like this, someone took control of my token I found out when I sent money it went to the new address instead of me

[@EatTheBlocks]

What you are saying does not make any sense.

[@ChamaraAriyarathne]

Ok, to be honest, this video is useless, because he doesn't deploy and show what's actually happening.