title: How can i update a variable everytime my smart contract receives ETH?
body: <p>So the last couple of weeks I spent my freetime on working on a dApp and I'm almost finished there's one last thing I have to implement but I really struggle to do so.</p>
  <p>So my dApp is basically a game. To get more players I added a token which the players can earn. I want them to stake their tokens to receive some of the profit the game makes. All the ETH the game makes goes into a treasury contract. That's the same contract where people can stake their tokens. I want them to have a &quot;pending ETH reward&quot; which they can withdraw on their cost. Similar to sushiswap with the difference that there isn't a fixed amount of reward per block. So basically I want the smart contract to assign the Ether it receives to the token stakers based on how much they stake. I don't want the Eth to directly get send to the addresses of the stakers because this would be to pricy.</p>
  <p>At first I thought this would be easy but than I looked into it, wasted many hours and found out that I have no clue how to do this. How can I let my contract know that it received ETH and that it should do something evertime it receives Eth? Every type of help is highly appreciated!</p>
  <p>My current idea is to make a struct array called &quot;Users&quot;. Each User stores the adress, pendingETHreward and amount of staked tokens. Each User should be mapped to the addres of the user. The Problem: I dont know how to update the variable pendingETHreward of each user everytime the contract receives ETH.</p>