Created
October 29, 2021 19:59
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total supply erc20 token
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pragma solidity >=0.6.0 <0.8.0; | |
import "../../GSN/Context.sol"; | |
import "./IERC20.sol"; | |
import "../../math/SafeMath.sol"; | |
contract ERC20 is Context, IERC20 { | |
using SafeMath for uint256; | |
mapping (address => uint256) private _balances; | |
mapping (address => mapping (address => uint256)) private _allowances; | |
uint256 private _totalSupply; | |
string private _name; | |
string private _symbol; | |
uint8 private _decimals; | |
constructor (string memory name_, string memory symbol_) public { | |
_name = name_; | |
_symbol = symbol_; | |
_decimals = 18; | |
} | |
function name() public view returns (string memory) { | |
return _name; | |
} | |
function symbol() public view returns (string memory) { | |
return _symbol; | |
} | |
function decimals() public view returns (uint8) { | |
return _decimals; | |
} | |
function totalSupply() public view override returns (uint256) { | |
return _totalSupply; | |
} | |
function balanceOf(address account) public view override returns (uint256) { | |
return _balances[account]; | |
} | |
function transfer(address recipient, uint256 amount) public virtual override returns (bool) { | |
_transfer(_msgSender(), recipient, amount); | |
return true; | |
} | |
function allowance(address owner, address spender) public view virtual override returns (uint256) { | |
return _allowances[owner][spender]; | |
} | |
function approve(address spender, uint256 amount) public virtual override returns (bool) { | |
_approve(_msgSender(), spender, amount); | |
return true; | |
} | |
function transferFrom(address sender, address recipient, uint256 amount) public virtual override returns (bool) { | |
_transfer(sender, recipient, amount); | |
_approve(sender, _msgSender(), _allowances[sender][_msgSender()].sub(amount, "ERC20: transfer amount exceeds allowance")); | |
return true; | |
} | |
function increaseAllowance(address spender, uint256 addedValue) public virtual returns (bool) { | |
_approve(_msgSender(), spender, _allowances[_msgSender()][spender].add(addedValue)); | |
return true; | |
} | |
function decreaseAllowance(address spender, uint256 subtractedValue) public virtual returns (bool) { | |
_approve(_msgSender(), spender, _allowances[_msgSender()][spender].sub(subtractedValue, "ERC20: decreased allowance below zero")); | |
return true; | |
} | |
function _transfer(address sender, address recipient, uint256 amount) internal virtual { | |
require(sender != address(0), "ERC20: transfer from the zero address"); | |
require(recipient != address(0), "ERC20: transfer to the zero address"); | |
_beforeTokenTransfer(sender, recipient, amount); | |
_balances[sender] = _balances[sender].sub(amount, "ERC20: transfer amount exceeds balance"); | |
_balances[recipient] = _balances[recipient].add(amount); | |
emit Transfer(sender, recipient, amount); | |
} | |
function _mint(address account, uint256 amount) internal virtual { | |
require(account != address(0), "ERC20: mint to the zero address"); | |
_beforeTokenTransfer(address(0), account, amount); | |
_totalSupply = _totalSupply.add(amount); | |
_balances[account] = _balances[account].add(amount); | |
emit Transfer(address(0), account, amount); | |
} | |
function _burn(address account, uint256 amount) internal virtual { | |
require(account != address(0), "ERC20: burn from the zero address"); | |
_beforeTokenTransfer(account, address(0), amount); | |
_balances[account] = _balances[account].sub(amount, "ERC20: burn amount exceeds balance"); | |
_totalSupply = _totalSupply.sub(amount); | |
emit Transfer(account, address(0), amount); | |
} | |
function _approve(address owner, address spender, uint256 amount) internal virtual { | |
require(owner != address(0), "ERC20: approve from the zero address"); | |
require(spender != address(0), "ERC20: approve to the zero address"); | |
_allowances[owner][spender] = amount; | |
emit Approval(owner, spender, amount); | |
} | |
function _setupDecimals(uint8 decimals_) internal { | |
_decimals = decimals_; | |
} | |
function _beforeTokenTransfer(address from, address to, uint256 amount) internal virtual { } | |
} |
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