smart_contract_dataset/integer overflow/34.sol

pragma solidity ^0.4.18;

contract owned {
    address public owner;

    constructor() public {
        owner = msg.sender;
    }

    modifier onlyOwner {
        require(msg.sender == owner);
        _;
    }

    function transferOwnership(address newOwner) onlyOwner public {
        owner = newOwner;
    }

    function destruct() public onlyOwner {
        selfdestruct(owner);
    }
}


interface tokenRecipient { function receiveApproval(address _from, uint256 _value, address _token, bytes _extraData) external; }


contract TokenERC20 {
    string public name;
    string public symbol;
    uint8 public decimals = 18;
    uint256 public totalSupply;

    
    mapping (address => uint256) public balanceOf;
    mapping (address => mapping (address => uint256)) public allowance;

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

    
    event Burn(address indexed from, uint256 value);

    
    constructor() public {
        totalSupply = 10000000 * 10 ** uint256(decimals);  
        balanceOf[msg.sender] = totalSupply;                
        name = 'Global Gold Cash';                          
        symbol = "GGC";                               
    }

    
    function _transfer(address _from, address _to, uint _value) internal {
        require(_to != 0x0);                        
        require(balanceOf[_from] >= _value);        
        require(balanceOf[_to] + _value > balanceOf[_to]);  
        uint previousBalances = balanceOf[_from] + balanceOf[_to];  
        balanceOf[_from] -= _value;                     
        balanceOf[_to] += _value;                       
        emit Transfer(_from, _to, _value);
        assert(balanceOf[_from] + balanceOf[_to] == previousBalances);      
    }

    
    function transfer(address _to, uint256 _value) public {
        _transfer(msg.sender, _to, _value);
    }

    
    function transferFrom(address _from, address _to, uint256 _value) public returns (bool success) {
        require(_value <= allowance[_from][msg.sender]);     
        allowance[_from][msg.sender] -= _value;
        _transfer(_from, _to, _value);
        return true;
    }

    
    function approve(address _spender, uint256 _value) public
        returns (bool success) {
        allowance[msg.sender][_spender] = _value;
        return true;
    }

    
    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;
        }
    }

    
    function burn(uint256 _value) public returns (bool success) {
        require(balanceOf[msg.sender] >= _value);   
        balanceOf[msg.sender] -= _value;            
        totalSupply -= _value;                      
        emit Burn(msg.sender, _value);
        return true;
    }

    
    function burnFrom(address _from, uint256 _value) public returns (bool success) {
        require(balanceOf[_from] >= _value);                
        require(_value <= allowance[_from][msg.sender]);    
        balanceOf[_from] -= _value;                         
        allowance[_from][msg.sender] -= _value;             
        totalSupply -= _value;                              
        emit Burn(_from, _value);
        return true;
    }
}


contract GlobalGoldCashToken is owned, TokenERC20 {

    uint256 public decimals = 18;
    string  public tokenName;
    string  public tokenSymbol;
    uint minBalanceForAccounts ;                                         

    mapping (address => bool) public frozenAccount;

    
    event FrozenFunds(address target, bool frozen);

    

    
    constructor() public {
        owner = msg.sender;
        totalSupply = 1000000000000000000;
        balanceOf[owner]=totalSupply;
        tokenName="Global Gold Cash";
        tokenSymbol="GGC";
    }


    
    function _transfer(address _from, address _to, uint _value) internal {
        require (_to != 0x0);                               
        require (balanceOf[_from] >= _value);               
        require (balanceOf[_to] + _value > balanceOf[_to]); 
        require(!frozenAccount[_from]);                     
        require(!frozenAccount[_to]);                       
        balanceOf[_from] -= _value;                         
        balanceOf[_to] += _value;                           
        emit Transfer(_from, _to, _value);
    }

    
    
    
    function mintToken(address target, uint256 mintedAmount) onlyOwner public {
        balanceOf[target] += mintedAmount;
        totalSupply += mintedAmount;
        emit Transfer(0, this, mintedAmount);
        emit Transfer(this, target, mintedAmount);
    }

    
    
    
    function freezeAccount(address target, bool freeze) onlyOwner public {
        frozenAccount[target] = freeze;
        emit FrozenFunds(target, freeze);
    }
}