Ether balance on Metamask doesn't change after selling tokens

Question

I create a smart contract successfully using Remix IDE , Metamask and Ropsten for testing.

I want to sell some tokens using Sell function, so I specified the value "20" for Sell function ,my initial balance was 600 after that I checked the balanceOf , the new value is 580,but my Ether Balance on Metamask didn't change. My sell function code is :

 function sell(uint amount)public returns (uint revenue){
        require(balanceOf[msg.sender] >= amount);        
        balanceOf[this] += amount;                      
        balanceOf[msg.sender] -= amount;                  
        revenue = amount / sellPrice;                    
        msg.sender.transfer(revenue);                    
        emit Transfer(msg.sender, this, amount);         
        result = amount;
        return revenue;                                 
    }

Answer 1

I'm guessing the function returns 0 as revenue. That's quite typical for when trying to calculate floating point numbers.

You can read more about how to do division for example here: How can I perform float type division in solidity?