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 {setupDecimals} is called. 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}.
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.
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.
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.