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- pragma solidity ^0.4.16;
- interface tokenRecipient { function receiveApproval(address _from, uint256 _value, address _token, bytes _extraData) external; }
- contract TokenERC20 {
- // Public variables of the token
- string public name;
- string public symbol;
- uint8 public decimals = 10;
- // 18 decimals is the strongly suggested default, avoid changing it
- uint256 public totalSupply;
- // This creates an array with all balances
- mapping (address => uint256) public balanceOf;
- mapping (address => mapping (address => uint256)) public allowance;
- // This generates a public event on the blockchain that will notify clients
- event Transfer(address indexed from, address indexed to, uint256 value);
- // This notifies clients about the amount burnt
- event Burn(address indexed from, uint256 value);
- /**
- * Constructor function
- *
- * Initializes contract with initial supply tokens to the creator of the contract
- */
- function TokenERC20(
- uint256 initialSupply,
- string tokenName,
- string tokenSymbol
- ) public {
- totalSupply = initialSupply * 10 ** uint256(decimals); // Update total supply with the decimal amount
- balanceOf[msg.sender] = totalSupply; // Give the creator all initial tokens
- name = tokenName; // Set the name for display purposes
- symbol = tokenSymbol; // Set the symbol for display purposes
- }
- /**
- * Internal transfer, only can be called by this contract
- */
- function _transfer(address _from, address _to, uint _value) internal {
- // Prevent transfer to 0x0 address. Use burn() instead
- require(_to != 0x0);
- // Check if the sender has enough
- require(balanceOf[_from] >= _value);
- // Check for overflows
- require(balanceOf[_to] + _value >= balanceOf[_to]);
- // Save this for an assertion in the future
- uint previousBalances = balanceOf[_from] + balanceOf[_to];
- // Subtract from the sender
- balanceOf[_from] -= _value;
- // Add the same to the recipient
- balanceOf[_to] += _value;
- emit Transfer(_from, _to, _value);
- // Asserts are used to use static analysis to find bugs in your code. They should never fail
- assert(balanceOf[_from] + balanceOf[_to] == previousBalances);
- }
- /**
- * Transfer tokens
- *
- * Send `_value` tokens to `_to` from your account
- *
- * @param _to The address of the recipient
- * @param _value the amount to send
- */
- function transfer(address _to, uint256 _value) public {
- _transfer(msg.sender, _to, _value);
- }
- /**
- * Transfer tokens from other address
- *
- * Send `_value` tokens to `_to` on behalf of `_from`
- *
- * @param _from The address of the sender
- * @param _to The address of the recipient
- * @param _value the amount to send
- */
- function transferFrom(address _from, address _to, uint256 _value) public returns (bool success) {
- require(_value <= allowance[_from][msg.sender]); // Check allowance
- allowance[_from][msg.sender] -= _value;
- _transfer(_from, _to, _value);
- return true;
- }
- /**
- * Set allowance for other address
- *
- * Allows `_spender` to spend no more than `_value` tokens on your behalf
- *
- * @param _spender The address authorized to spend
- * @param _value the max amount they can spend
- */
- function approve(address _spender, uint256 _value) public
- returns (bool success) {
- allowance[msg.sender][_spender] = _value;
- return true;
- }
- /**
- * Set allowance for other address and notify
- *
- * Allows `_spender` to spend no more than `_value` tokens on your behalf, and then ping the contract about it
- *
- * @param _spender The address authorized to spend
- * @param _value the max amount they can spend
- * @param _extraData some extra information to send to the approved contract
- */
- function approveAndCall(address _spender, uint256 _value, bytes _extraData)
- public
- returns (bool success) {
- tokenRecipient spender = tokenRecipient(_spender);
- if (approve(_spender, _value)) {
- spender.receiveApproval(msg.sender, _value, this, _extraData);
- return true;
- }
- }
- /**
- * Destroy tokens
- *
- * Remove `_value` tokens from the system irreversibly
- *
- * @param _value the amount of money to burn
- */
- function burn(uint256 _value) public returns (bool success) {
- require(balanceOf[msg.sender] >= _value); // Check if the sender has enough
- balanceOf[msg.sender] -= _value; // Subtract from the sender
- totalSupply -= _value; // Updates totalSupply
- emit Burn(msg.sender, _value);
- return true;
- }
- /**
- * Destroy tokens from other account
- *
- * Remove `_value` tokens from the system irreversibly on behalf of `_from`.
- *
- * @param _from the address of the sender
- * @param _value the amount of money to burn
- */
- function burnFrom(address _from, uint256 _value) public returns (bool success) {
- require(balanceOf[_from] >= _value); // Check if the targeted balance is enough
- require(_value <= allowance[_from][msg.sender]); // Check allowance
- balanceOf[_from] -= _value; // Subtract from the targeted balance
- allowance[_from][msg.sender] -= _value; // Subtract from the sender's allowance
- totalSupply -= _value; // Update totalSupply
- emit Burn(_from, _value);
- return true;
- }
- }
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