How to set token price in solidity

Question

I've tried

contract OToken {

using SafeMath for uint256;

uint public _totalSupply = 0;
uint public constant _cap = 100000000;
string public constant symbol = "OXN";
string public constant name = "OToken";
uint public constant decimals = 18;

uint public oneTokenInWei = 183.602;

If I want the token price to be $0.02 each and 1 eth is trading at $167 then 1 wei = 183.602 tokens

I can call this function if I want to change the price per token to .03

 function setOneTokenInWei(uint w) onlyOwner {
    oneTokenInWei = w;
    changed(msg.sender);
}

then this function to create the token

function createTokens() payable{

    require(
        msg.value > 0
        && _totalSupply < _cap
        && CROWDSALE_PAUSED <1
        );

        uint multiplier = 10 ** decimals;
        uint256 tokens = msg.value.mul(multiplier) / oneTokenInWei;

        balances[msg.sender] = balances[msg.sender].add(tokens);
        _totalSupply = _totalSupply.add(tokens);
        owner.transfer(msg.value);
}

this is not adding the current value to the senders wallet

Answer 1

We know that 1 Ether = 10¹⁸ wei, if we take that 1 Ether = $ 167

Then for $ 0.02 we should get $ 0.02 / $ 167 = 0.00011976047904191617 Ethers.

This equals to 10¹⁸ x 0.00011976047904191617 = 119760479041916.17 wei.

So if you put 1 Ether you will get 10¹⁸ / 119760479041916.17 = 8350 tokens.

At the price of $ 167 each token value is 167 / 8350 = 0.02 as desired.

I'd define a function so you can set the price of one ether and it derive the price of one token at two cents.

function setEthPrice(uint _etherPrice) onlyOwner {
    oneTokenInWei = 1 ether * 2 / _etherPrice / 100;
    changed(msg.sender);
}

Comments

is the _etherPrice agrument's price in the ether or the dollar ??

---

Hi, @There,

Ethereum is an alternative digital currency to bitcoin and had been trading as high as $352 on Wednesday. It has since rebounded from its flash-crash lows to trade to about $325 on the GDAX exchange. According to industry and price tracking website Coinmarketcap, which takes into account the price on several exchanges, ethereum was trading around $338.