SimpleToken.sol

pragma solidity ^0.4.16;

contract MyToken {
  /* This creates an array with all balances */
  mapping (address => uint256) public balanceOf;

  /* Initializes contract with initial supply tokens to the creator of the contract */
  function MyToken(
    uint256 initialSupply
  ) public {
    balanceOf[msg.sender] = initialSupply;              // Give the creator all initial tokens
  }

  /* Send coins */
  function transfer(address _to, uint256 _value) public {
    require(balanceOf[msg.sender] >= _value);           // Check if the sender has enough
    require(balanceOf[_to] + _value >= balanceOf[_to]); // Check for overflows
    balanceOf[msg.sender] -= _value;                    // Subtract from the sender
    balanceOf[_to] += _value;                           // Add the same to the recipient
  }
}