> For the complete documentation index, see [llms.txt](https://docs.fringe.fi/smart-contract-documentation/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://docs.fringe.fi/smart-contract-documentation/openzeppelin/contracts/token/erc20/extensions/erc20flashmint.md). # ERC 20 Flash Mint *Implementation of the ERC3156 Flash loans extension, as defined in ]. Adds the {flashLoan} method, which provides flash loan support at the token level. By default there is no fee, but this can be changed by overriding {flashFee}. Available since v4.1.* ## Methods ### allowance ```solidity function allowance(address owner, address spender) external view returns (uint256) ``` *See {IERC20-allowance}.* #### Parameters | Name | Type | Description | | ------- | ------- | ----------- | | owner | address | undefined | | spender | address | undefined | #### Returns | Name | Type | Description | | ---- | ------- | ----------- | | \_0 | uint256 | undefined | ### approve ```solidity function approve(address spender, uint256 amount) external nonpayable returns (bool) ``` *See {IERC20-approve}. Requirements: - `spender` cannot be the zero address.* #### Parameters | Name | Type | Description | | ------- | ------- | ----------- | | spender | address | undefined | | amount | uint256 | undefined | #### Returns | Name | Type | Description | | ---- | ---- | ----------- | | \_0 | bool | undefined | ### balanceOf ```solidity function balanceOf(address account) external view returns (uint256) ``` *See {IERC20-balanceOf}.* #### Parameters | Name | Type | Description | | ------- | ------- | ----------- | | account | address | undefined | #### Returns | Name | Type | Description | | ---- | ------- | ----------- | | \_0 | uint256 | undefined | ### decimals ```solidity function decimals() external view returns (uint8) ``` *Returns the number of decimals used to get its user representation. For example, if `decimals` equals `2`, a balance of `505` tokens should be displayed to a user as `5.05` (`505 / 10 ** 2`). Tokens usually opt for a value of 18, imitating the relationship between Ether and Wei. This is the value {ERC20} uses, unless this function is overridden; NOTE: This information is only used for display purposes: it in no way affects any of the arithmetic of the contract, including {IERC20-balanceOf} and {IERC20-transfer}.* #### Returns | Name | Type | Description | | ---- | ----- | ----------- | | \_0 | uint8 | undefined | ### decreaseAllowance ```solidity function decreaseAllowance(address spender, uint256 subtractedValue) external nonpayable returns (bool) ``` *Atomically decreases the allowance granted to `spender` by the caller. This is an alternative to {approve} that can be used as a mitigation for problems described in {IERC20-approve}. Emits an {Approval} event indicating the updated allowance. Requirements: - `spender` cannot be the zero address. - `spender` must have allowance for the caller of at least `subtractedValue`.* #### Parameters | Name | Type | Description | | --------------- | ------- | ----------- | | spender | address | undefined | | subtractedValue | uint256 | undefined | #### Returns | Name | Type | Description | | ---- | ---- | ----------- | | \_0 | bool | undefined | ### flashFee ```solidity function flashFee(address token, uint256 amount) external view returns (uint256) ``` *Returns the fee applied when doing flash loans. By default this implementation has 0 fees. This function can be overloaded to make the flash loan mechanism deflationary.* #### Parameters | Name | Type | Description | | ------ | ------- | ---------------------------------- | | token | address | The token to be flash loaned. | | amount | uint256 | The amount of tokens to be loaned. | #### Returns | Name | Type | Description | | ---- | ------- | ------------------------------------------------- | | \_0 | uint256 | The fees applied to the corresponding flash loan. | ### flashLoan ```solidity function flashLoan(contract IERC3156FlashBorrower receiver, address token, uint256 amount, bytes data) external nonpayable returns (bool) ``` *Performs a flash loan. New tokens are minted and sent to the `receiver`, who is required to implement the {IERC3156FlashBorrower} interface. By the end of the flash loan, the receiver is expected to own amount + fee tokens and have them approved back to the token contract itself so they can be burned.* #### Parameters | Name | Type | Description | | -------- | ------------------------------ | --------------------------------------------------------------------------------------------------- | | receiver | contract IERC3156FlashBorrower | The receiver of the flash loan. Should implement the {IERC3156FlashBorrower.onFlashLoan} interface. | | token | address | The token to be flash loaned. Only `address(this)` is supported. | | amount | uint256 | The amount of tokens to be loaned. | | data | bytes | An arbitrary datafield that is passed to the receiver. | #### Returns | Name | Type | Description | | ---- | ---- | ---------------------------------------- | | \_0 | bool | `true` is the flash loan was successful. | ### increaseAllowance ```solidity function increaseAllowance(address spender, uint256 addedValue) external nonpayable returns (bool) ``` *Atomically increases the allowance granted to `spender` by the caller. This is an alternative to {approve} that can be used as a mitigation for problems described in {IERC20-approve}. Emits an {Approval} event indicating the updated allowance. Requirements: - `spender` cannot be the zero address.* #### Parameters | Name | Type | Description | | ---------- | ------- | ----------- | | spender | address | undefined | | addedValue | uint256 | undefined | #### Returns | Name | Type | Description | | ---- | ---- | ----------- | | \_0 | bool | undefined | ### maxFlashLoan ```solidity function maxFlashLoan(address token) external view returns (uint256) ``` *Returns the maximum amount of tokens available for loan.* #### Parameters | Name | Type | Description | | ----- | ------- | ------------------------------------------- | | token | address | The address of the token that is requested. | #### Returns | Name | Type | Description | | ---- | ------- | -------------------------------------- | | \_0 | uint256 | The amont of token that can be loaned. | ### name ```solidity function name() external view returns (string) ``` *Returns the name of the token.* #### Returns | Name | Type | Description | | ---- | ------ | ----------- | | \_0 | string | undefined | ### symbol ```solidity function symbol() external view returns (string) ``` *Returns the symbol of the token, usually a shorter version of the name.* #### Returns | Name | Type | Description | | ---- | ------ | ----------- | | \_0 | string | undefined | ### totalSupply ```solidity function totalSupply() external view returns (uint256) ``` *See {IERC20-totalSupply}.* #### Returns | Name | Type | Description | | ---- | ------- | ----------- | | \_0 | uint256 | undefined | ### transfer ```solidity function transfer(address recipient, uint256 amount) external nonpayable returns (bool) ``` *See {IERC20-transfer}. Requirements: - `recipient` cannot be the zero address. - the caller must have a balance of at least `amount`.* #### Parameters | Name | Type | Description | | --------- | ------- | ----------- | | recipient | address | undefined | | amount | uint256 | undefined | #### Returns | Name | Type | Description | | ---- | ---- | ----------- | | \_0 | bool | undefined | ### transferFrom ```solidity function transferFrom(address sender, address recipient, uint256 amount) external nonpayable returns (bool) ``` *See {IERC20-transferFrom}. Emits an {Approval} event indicating the updated allowance. This is not required by the EIP. See the note at the beginning of {ERC20}. Requirements: - `sender` and `recipient` cannot be the zero address. - `sender` must have a balance of at least `amount`. - the caller must have allowance for `sender`'s tokens of at least `amount`.* #### Parameters | Name | Type | Description | | --------- | ------- | ----------- | | sender | address | undefined | | recipient | address | undefined | | amount | uint256 | undefined | #### Returns | Name | Type | Description | | ---- | ---- | ----------- | | \_0 | bool | undefined | ## Events ### Approval ```solidity event Approval(address indexed owner, address indexed spender, uint256 value) ``` #### Parameters | Name | Type | Description | | ----------------- | ------- | ----------- | | owner `indexed` | address | undefined | | spender `indexed` | address | undefined | | value | uint256 | undefined | ### Transfer ```solidity event Transfer(address indexed from, address indexed to, uint256 value) ``` #### Parameters | Name | Type | Description | | -------------- | ------- | ----------- | | from `indexed` | address | undefined | | to `indexed` | address | undefined | | value | uint256 | undefined | --- # Agent Instructions This documentation is published with GitBook. GitBook is the documentation platform designed so that both humans and AI agents can read, navigate, and reason over technical content effectively. Learn more at gitbook.com. ## Querying This Documentation If you need additional information that is not directly available in this page, you can query the documentation dynamically by asking a question. Perform an HTTP GET request on the current page URL with the `ask` query parameter: ``` GET https://docs.fringe.fi/smart-contract-documentation/openzeppelin/contracts/token/erc20/extensions/erc20flashmint.md?ask= ``` The question should be specific, self-contained, and written in natural language. The response will contain a direct answer to the question and relevant excerpts and sources from the documentation. Use this mechanism when the answer is not explicitly present in the current page, you need clarification or additional context, or you want to retrieve related documentation sections.