# PNC-20

**ERC-20**\*\*\*\*\*\*\*\* // SPDX-License-Identifier: MIT

pragma solidity >=0.6.0 <0.8.0;

### Library SafeMath

```
Library SafeMath 
{
function add(uint256 a, uint256 b) internal pure returns (uint256) {
    uint256 c = a + b;
    require(c >= a, "SafeMath: addition overflow");
    return c;
}
function sub(uint256 a, uint256 b) internal pure returns (uint256) {
    return sub(a, b, "SafeMath: subtraction overflow");
}
function sub(uint256 a, uint256 b, string memory errorMessage) internal pure returns (uint256) {
    require(b <= a, errorMessage);
    uint256 c = a - b;
    return c;
}
function mul(uint256 a, uint256 b) internal pure returns (uint256) {
    // Gas optimization: this is cheaper than requiring 'a' not being zero, but the
    // benefit is lost if 'b' is also tested.
    // See: https://github.com/OpenZeppelin/openzeppelin-contracts/pull/522
    if (a == 0) {
        return 0;
    }
    uint256 c = a * b;
    require(c / a == b, "SafeMath: multiplication overflow");
    return c;
}
function div(uint256 a, uint256 b) internal pure returns (uint256) {
    return div(a, b, "SafeMath: division by zero");
}
function div(uint256 a, uint256 b, string memory errorMessage) internal pure returns (uint256) {
    require(b > 0, errorMessage);
    uint256 c = a / b;
    // assert(a == b * c + a % b); // There is no case in which this doesn't hold
    return c;
}
function mod(uint256 a, uint256 b) internal pure returns (uint256) {
    return mod(a, b, "SafeMath: modulo by zero");
}
function mod(uint256 a, uint256 b, string memory errorMessage) internal pure returns (uint256) {
    require(b != 0, errorMessage);
    return a % b;
}
}
```

### Abstract contract Context

Abstract contract Context { function \_msgSender() internal view virtual returns (address payable) { return msg.sender; }

```
function _msgData() internal view virtual returns (bytes memory) 
{
    this; // silence state mutability warning without generating bytecode - see https://github.com/ethereum/solidity/issues/2691
    return msg.data;
}
```

### Interface IERC20

```
Interface IERC20 
{
function totalSupply() external view returns (uint256);

function balanceOf(address account) external view returns (uint256);

function transfer(address recipient, uint256 amount) external returns (bool);

function allowance(address owner, address spender) external view returns (uint256);

function approve(address spender, uint256 amount) external returns (bool);

function transferFrom(address sender, address recipient, uint256 amount) external returns (bool);

event Transfer(address indexed from, address indexed to, uint256 value);

event Approval(address indexed owner, address indexed spender, uint256 value);
}
```

### Contract MintableERC20

Contract MintableERC20 is Context,&#x20;

```
IERC20 
{ using SafeMath for uint256;
mapping (address => uint256) private _balances;
mapping (address => mapping (address => uint256)) private _allowances;
address private _admin;
bool private _mintable;
uint256 private _totalSupply;
string private _name;
string private _symbol;
uint8 private _decimals;
constructor (string memory name_, string memory symbol_, uint8 decimals_, uint256 initialSupply_, bool mintable_) public {
    require(msg.sender != address(0x0), "cannot deploy the token from address 0x0");
    _name = name_;
    _symbol = symbol_;
    _decimals = decimals_;
    _admin = msg.sender;
    _mint(_admin, initialSupply_);
    _mintable = mintable_;
}
    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 mintable() public view returns (bool) {
    return _mintable;
}
    function mint(uint256 amount) public returns (bool) {
    require(_mintable, "the token is not mintable");
    require(msg.sender == _admin, "only admin can mint new tokens");
    _mint(_admin, amount);
    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");

    _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");

    _totalSupply = _totalSupply.add(amount);
    _balances[account] = _balances[account].add(amount);
    emit Transfer(address(0), account, 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);
}
}
```


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