IERC20
View Source: contracts/interfaces/IERC20.sol
↘ Derived Contracts: IERC20Metadata
IERC20
Functions
- totalSupply()
- balanceOf(address account)
- transfer(address to, uint256 amount)
- allowance(address owner, address spender)
- approve(address spender, uint256 amount)
- transferFrom(address from, address to, uint256 amount)
totalSupply
Returns the amount of tokens in existence.
function totalSupply()
external
view
returns(uint256)
Returns
uint256
balanceOf
Returns the amount of tokens owned by account.
function balanceOf(address account)
external
view
returns(uint256)
Arguments
| Name | Type | Description |
|---|---|---|
| account | address |
Returns
uint256
transfer
Moves amount 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 amount)
external
returns(bool)
Arguments
| Name | Type | Description |
|---|---|---|
| to | address | |
| amount | uint256 |
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)
Arguments
| Name | Type | Description |
|---|---|---|
| owner | address | |
| spender | address |
Returns
uint256
approve
Sets amount 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 amount)
external
returns(bool)
Arguments
| Name | Type | Description |
|---|---|---|
| spender | address | |
| amount | uint256 |
Returns
bool
transferFrom
Moves amount tokens from from to to using the
allowance mechanism. amount 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 amount)
external
returns(bool)
Arguments
| Name | Type | Description |
|---|---|---|
| from | address | |
| to | address | |
| amount | uint256 |
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
)
Parameters
| Name | Type | Description |
|---|---|---|
| from | address | |
| to | address | |
| value | uint256 |
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
)
Parameters
| Name | Type | Description |
|---|---|---|
| owner | address | |
| spender | address | |
| value | uint256 |