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You should store them all in one contract; there's no reason to create an arbitrary amount of contracts. In Solidity, you can use a dynamically sized array to store all the posts. A simple example wo …

As the amount of players grows, that loop will consume more and more gas. If you get a lot of players, it will start to cost too much in transaction fees. If the amount of players should be unlimited, …

You cannot do this using the ERC20 transfer(..) function. You will need to call the transferFrom(..) function on the ERC20 contract. To be able to use transferFrom(..), your [Sender] will first have …

You can use the encodeParameters function of web3.js function to convert the function arguments into a hexadecimal string. Here's a documentation link: https://web3js.readthedocs.io/en/1.0/web3-eth-a …

Variables behave like functions from the perspective of other contracts. The error is telling you that b._addr is not an address, but a function that returns an address. In contract A, try doing b._ …

Contracts don't have a private key, so they can't sign anything with it. In fact, contract addresses don't have anything to do with public/private key cryptography. Contract addresses are the hash of …

Could you share your contract code so we can try to see what's causing the high deployment cost? There may or may not be an easy solution to this problem. You should check how much gas is being spent …

The msg.value contains an amount in wei, not an amount in Ether. 1 Ether is equal to 1000000000000000000 wei, so if you send 1 ether to your function the value of msg.value will be 100000000000000000 …

All data stored inside a smart contract (in the blockchain) is always publicly accessible. All the data that the code of the smart contract can access, can be accessed by everyone. The data is not e …

If some code reverts/throws the current contract call will have no effects, but not necessarily the entire transaction. The assembly instruction CALL to code that reverted will return false to indicat …

Enums defined inside a contract are by default accessible from other contracts. In Producer you can use the expressions: Supplier.State.inactive Supplier.State.active Supplier.State.kaput Your cod …

uint256 is generally used for: Addresses Numbers Account balances Doing math like + - * / or ** bytes32 is generally used for: Small strings of no more than 32 characters Hashes (the sha3(..) fu …

It's good practice to explicitly use memory or storage to clarify whether a variable contains a pointer to memory or storage. You should not always use the memory keyword, because it could make your …

These kinds of things are fundamentally impossible. Front-end code by definition is running on the user's machine. The user controls their machine, so they control the front-end. Imagine a hypothetic …

I just looked at your transactions, and I see that you are not calling the paybackEther() function at all: 0x9afb64e3082d06e0915f7d89a2b436ae3f9f273630407b52662d3a5785933336 0xd70b7dae05ee903868fc93 …