Crowdsale-Vertragsfehler

Unten ist das Skript, das ich geschrieben habe, aber ich kann es nicht ausführen, ich bekomme einige Nachrichten (die Reihenfolge der Nachrichten, die ich poste, ist zuerst die, die ich für das IERC20 und dann für das AAAtoken bekomme), zuerst ist das Skript für IERC20, die SafeMath, dann importiere ich diese beiden in das AAAtoken-Skript

pragma solidity ^0.4.11;

interface IERC20 {

function totalSupply() constant returns (uint256 totalSupply);

    function balanceOf(address_owner) constant returns (uint256 balance);
    function transfer(address_to, uint256_value) returns(bool success);
    function transferFrom(address_from, address_to, uint256_value) returns(bool success);
    function approve(address_spender, uint256_value) returns(bool success);
    function allowance(address_owner, address_spender) constant returns(uint256 remaining);
    event Transfer(address indexed_from, address indexed_to, uint256_value);
    event Approval(address indexed_owner, address indexed_spender, uint256_value);


}

pragma solidity ^0.4.18;



/**
 * @title SafeMath
 * @dev Math operations with safety checks that throw on error
 */

library SafeMath {

  /**
  * @dev Multiplies two numbers, throws on overflow.
  */
  function mul(uint256 a, uint256 b) internal pure returns (uint256) {
    if (a == 0) {
      return 0;
    }
    uint256 c = a * b;
    assert(c / a == b);
    return c;
  }

  /**
  * @dev Integer division of two numbers, truncating the quotient.
  */

function div(uint256 a, uint256 b) internal pure returns (uint256) {
    // assert(b > 0); // Solidity automatically throws when dividing by 0
    uint256 c = a / b;
    // assert(a == b * c + a % b); // There is no case in which this doesn't hold
    return c;
  }

pragma solidity ^0.4.11;

import './IERC20.sol';
import './SafeMath.sol';

contract AAAtoken is IERC20{

    using SafeMath for uint256;

    uint public _totalSupply=0;
    string public constant symbol = "AAA";
    string public constant name= "AAA Token";
    uint8  public constant decimals = 18;

    // 1 Ether = 500 AAA
    uint256 public constant RATE = 500;
    address public owner;
    mapping(address=>uint256) balances;
    mapping(address=> mapping(address=> uint256)) allowed;


    function() payable {
        createTokens();

    }

    function AAAtoken(){
        owner=msg.sender;

    }

    function createTokens() payable {
        require(msg.value > 0);
        uint256 tokens = msg.value.mul(RATE);
        balances[msg.sender] = balances[msg.sender].add(tokens);
        _totalSupply = _totalSupply.add(tokens);
        owner.transfer(msg.value);

    }



    function totalSupply() constant returns (uint256 totalSupply){

        return _totalSupply;


    }
    function balanceOf(address_owner) constant returns (uint256 balance){

        return balances[_owner];


    }
    function transfer(address_to, uint256_value) returns(bool success){

        require(
            balances[msg.sender] >= _value
            && _value > 0
        );
        balances[msg.sender]=balances[msg.sender].sub(_value);
        balances[_to]=balances[_to].add(_value);
        Transfer(msg.sender, _to, _value);
        return true;


    }
    function transferFrom(address_from, address_to, uint256_value) returns(bool success){

        require(
            allowed[_from][msg.sender] >= _value
            && balances[_from] >= _value
            && _value >0

        );
        balances[_from] =balances[_from].sub(_value);
        balances[_to] =balances[_to].add(_value);
        allowed[_from][msg.sender] =allowed[_from][msg.sender].sub(_value);
        Transfer(_from, _to, _value);
    return true;


    }
    function approve(address_spender, uint256_value) returns(bool success){

        allowed[msg.sender][_spender] = _value;
        Approval(msg.sender, _spender, _value);
        return true;


    }
    function allowance(address_owner, address_spender) constant returns(uint256 remaining){
        return allowed[_owner] [_spender];


    }
        event Transfer(address indexed_from, address indexed_to, uint256_value);
        event Approval(address indexed_owner, address indexed_spender, uint256_value);







}


//Messages for the IERC20

browser/IERC20.sol:4:5: Warning: No visibility specified. Defaulting to "public".
    function totalSupply() constant returns (uint256 totalSupply);
    ^------------------------------------------------------------^

browser/IERC20.sol:5:5: Warning: No visibility specified. Defaulting to "public".
    function balanceOf(address_owner) constant returns (uint256 balance);
    ^-------------------------------------------------------------------^
browser/IERC20.sol:6:5: Warning: No visibility specified. Defaulting to "public".
    function transfer(address_to, uint256_value) returns(bool success);
    ^-----------------------------------------------------------------^
browser/IERC20.sol:5:24: DeclarationError: Identifier not found or not unique.
    function balanceOf(address_owner) constant returns (uint256 balance);
                       ^-----------^


//Messages for the AAAtoken

browser/AAAtoken.sol:22:5: Warning: No visibility specified. Defaulting to "public".
    function() payable {
    ^

Spanning multiple lines.

browser/AAAtoken.sol:27:5: Warning: No visibility specified. Defaulting to "public".
    function AAAtoken(){
    ^

Spanning multiple lines.

browser/AAAtoken.sol:32:5: Warning: No visibility specified. Defaulting to "public".
    function createTokens() payable {
    ^

Spanning multiple lines.

browser/AAAtoken.sol:43:5: Warning: No visibility specified. Defaulting to "public".
    function totalSupply() constant returns (uint256 totalSupply){
    ^

Spanning multiple lines.

browser/AAAtoken.sol:49:5: Warning: No visibility specified. Defaulting to "public".
    function balanceOf(address_owner) constant returns (uint256 balance){
    ^
Spanning multiple lines.

browser/AAAtoken.sol:55:5: Warning: No visibility specified. Defaulting to "public".
    function transfer(address_to, uint256_value) returns(bool success){
    ^
Spanning multiple lines.

browser/AAAtoken.sol:68:5: Warning: No visibility specified. Defaulting to "public".
    function transferFrom(address_from, address_to, uint256_value) returns(bool success){
    ^
Spanning multiple lines.

browser/AAAtoken.sol:84:5: Warning: No visibility specified. Defaulting to "public".
    function approve(address_spender, uint256_value) returns(bool success){
    ^
Spanning multiple lines.

browser/AAAtoken.sol:92:5: Warning: No visibility specified. Defaulting to "public".
    function allowance(address_owner, address_spender) constant returns(uint256 remaining){
    ^
Spanning multiple lines.

browser/IERC20.sol:4:46: Warning: This declaration shadows an existing declaration.
    function totalSupply() constant returns (uint256 totalSupply);
                                             ^-----------------^
browser/IERC20.sol:4:5: The shadowed declaration is here:
    function totalSupply() constant returns (uint256 totalSupply);
    ^------------------------------------------------------------^

browser/AAAtoken.sol:43:46: Warning: This declaration shadows an existing declaration.
    function totalSupply() constant returns (uint256 totalSupply){
                                             ^-----------------^
browser/AAAtoken.sol:43:5: The shadowed declaration is here:
    function totalSupply() constant returns (uint256 totalSupply){
    ^
Spanning multiple lines.