IERC20
Interface of the ERC-20 standard as defined in the ERC.
Functions
totalSupply
Returns the value of tokens in existence.
function totalSupply() external view returns (uint256);
balanceOf
Returns the value of tokens owned by account
.
function balanceOf(address account) external view returns (uint256);
transfer
Moves a value
amount of tokens from the caller's account to to
.
Returns a boolean value indicating whether the operation succeeded.
Emits a Transfer event.
function transfer(address to, uint256 value) external returns (bool);
allowance
Returns the remaining number of tokens that spender
will be
allowed to spend on behalf of owner
through transferFrom. This is
zero by default.
This value changes when {approve} or {transferFrom} are called.
function allowance(address owner, address spender) external view returns (uint256);
approve
Sets a value
amount of tokens as the allowance of spender
over the
caller's tokens.
Returns a boolean value indicating whether the operation succeeded.
IMPORTANT: Beware that changing an allowance with this method brings the risk
that someone may use both the old and the new allowance by unfortunate
transaction ordering. One possible solution to mitigate this race
condition is to first reduce the spender's allowance to 0 and set the
desired value afterwards:
https://github.com/ethereum/EIPs/issues/20#issuecomment-263524729
Emits an Approval event.
function approve(address spender, uint256 value) external returns (bool);
transferFrom
Moves a value
amount of tokens from from
to to
using the
allowance mechanism. value
is then deducted from the caller's
allowance.
Returns a boolean value indicating whether the operation succeeded.
Emits a Transfer event.
function transferFrom(address from, address to, uint256 value) external returns (bool);
Events
Transfer
Emitted when value
tokens are moved from one account (from
) to
another (to
).
Note that value
may be zero.
event Transfer(address indexed from, address indexed to, uint256 value);
Approval
Emitted when the allowance of a spender
for an owner
is set by
a call to approve. value
is the new allowance.
event Approval(address indexed owner, address indexed spender, uint256 value);