Consequently, this token standard empowers developers of all types to accurately predict how new tokens will function within the larger Ethereum system. Here is, presented as an interface, the functions an ERC must implement. Here is a line-by-line explainer of what every function is for. Returns the amount of tokens in existence. This function is a getter and does not modify the state of the contract.
Keep in mind that there are no floats in Solidity. Therefore most tokens adopt 18 decimals and will return the total supply and other results as followed for 1 token. Not every token has 18 decimals and this is something you really need to watch for when dealing with tokens. Returns the amount of tokens owned by an address account. The ERC standard allows an address to give an allowance to another address to be able to retrieve tokens from it.
This getter returns the remaining number of tokens that the spender will be allowed to spend on behalf of owner. This function is a getter and does not modify the state of the contract and should return 0 by default. Moves the amount of tokens from the function caller address msg. This function emits the Transfer event defined later. It returns true if the transfer was possible.
Set the amount of allowance the spender is allowed to transfer from the function caller msg. This function emits the Approval event. The function returns whether the allowance was successfully set. Moves the amount of tokens from sender to recipient using the allowance mechanism. This function emits the Transfer event. Note that if we call the require function in the case of an error the ether sent will directly be reverted and given back to the user.
To keep things simple, we just exchange 1 token for 1 Wei. In the case where the buy is successful we should see two events in the transaction: The token Transfer and the Bought event. The function responsible for the sell will first require the user to have approved the amount by calling the approve function beforehand.
Here is the complete code for the tutorial:. Помогите перевести эту страничку. Перевести страничку. Что такое Ether ETH? Использование Ethereum.
Bitcoin, Litecoin, Etherium, Dash, Bitcoin Cash and Fiat in one multi-currency PAYEER® account! exchanging ether to tokens. We'll start our Decentralized exchange code by adding our simple ERC20 codebase: 1pragma. An introduction to deploying your first smart contract on an Ethereum 9 function transfer(address recipient, uint amount) external returns (bool);.