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When I deploy a contract with a function with receiver.transfer(), receiver.send() or a msg.value function, the function can't get executed when I try to interact with it (MyEtherWallet and web3 via metamask), so I'm wondering how to use the functions in Solidity.

Here are examples with incorrect code:

First try:

function buytokens() public payable{
    uint256 ethersent = msg.value / 1000000000000000000;
    address zender = msg.sender;
    uint256 tokens = ethersent * 10;
    require(balanceOf[owner] >= tokens);
    balanceOf[zender] += tokens;
    balanceOf[owner] -= tokens;
    tokenbuy(msg.sender, owner, ethersent, tokens);
}

Second try:

contract token{

mapping (address => uint256) public balanceOf;

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

function buy() public payable returns (uint amount){
    amount = msg.value;                    // calculates the amount
    require(balanceOf[this] >= amount);               // checks if it has enough to sell
    balanceOf[msg.sender] += amount;                  // adds the amount to buyer's balance
    balanceOf[this] -= amount;                        // subtracts amount from seller's balance
    Transfer(this, msg.sender, amount);               // execute an event reflecting the change
    return amount;                                    // ends function and returns
}

function sell(uint amount) public returns (uint revenue){
    require(balanceOf[msg.sender] >= amount);         // checks if the sender has enough to sell
    balanceOf[this] += amount;                        // adds the amount to owner's balance
    balanceOf[msg.sender] -= amount;                  // subtracts the amount from seller's balance
    revenue = amount;
    msg.sender.transfer(revenue);                     // sends ether to the seller: it's important to do this last to prevent recursion attacks
    Transfer(msg.sender, this, amount);               // executes an event reflecting on the change
    return revenue;                                   // ends function and returns
}

}

Third try (from example Token contract: https://ethereum.org/token):

function buy() payable public {
    uint amount = msg.value / buyPrice;               // calculates the amount
    _transfer(this, msg.sender, amount);              // makes the transfers
}

Could somebody tell me what I'm doing wrong?

criplingtrader
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  • When you say function not executed, what exactly does it mean? Can you be more specific about the steps you have tried? – Linmao Song Feb 09 '18 at 13:20
  • When in MyEtherWallet I try to interact with the contract I get the error that it would run out of gas (Gas Limit estimate -1), because there is an error in the code. – criplingtrader Feb 09 '18 at 13:23
  • Also, why cant you send ether to an payable function in the Remix Solidity IDE? – criplingtrader Feb 09 '18 at 13:24
  • This question has been answered here. https://ethereum.stackexchange.com/questions/19341/address-send-vs-address-transfer-best-practice-usage – Ray Zhu Aug 04 '20 at 07:37

0 Answers0