Are there any examples of using precompiled contracts?

The thing is I want to create my own custom precompiled contracts, and use it in my private chain of ethereum. Here is my code, but it is not right when I call hello.say() in geth attach line. In geth side, I changed core/vm/contracts.go file, add my custom contracts. var PrecompiledContractsHomestead = map[common.Address]PrecompiledContract{ common.BytesToAddress([]byte{1}): &ecrecover{},…

Invalid number value when deploying contract using truffle?

2_deploy_contracts.js Replacing ‘OraclizeTest’ Error: * Deployment Failed * “OraclizeTest” — invalid number value (arg=”_amount”, coderType=”uint256″, value={“from”:”0xb5Fb3E9BB73e742689F1001C519d6763a39A4Bc5″,”gas”:6721975,”value”:1000000000000000000}). at /root/.nvm/versions/node/v9.11.2/lib/node_modules/truffle/build/webpack:/packages/deployer/src/deployment.js:364:1 at at process._tickCallback (internal/process/next_tick.js:182:7) Truffle v5.1.8 (core: 5.1.8) Node v9.11.2 var OraclizeTest = artifacts.require(“./OraclizeTest.sol”); module.exports = function(deployer, network, accounts) { // Deploys the OraclizeTest contract and funds it with 0.5 ETH // The contract needs a balance…

What does it mean to declare an item of type contract?

Wasn’t quite sure how to word the title, but in the following code: contract KittyInterface { … } contract ZombieFeeding is ZombieFactory { KittyInterface kittyContract; } what is the declaration KittyInterface kittyContract; creating? I saw that it can be be initialized with KittyInterface kittyContract = KittyInterface(ckAddress); where ckAddress is the address of the interface contract…

transactions fails with my smart contract of etherdelta

I just tried to build smart contract etherdelta After using on my page chipuca.github.io i get the following error when do a deposit or anything else https://etherscan.io/tx/0x9b633cd278c07eca4757909c4174c39d707d5ee883a66fc0995072888696958d The contract is: https://github.com/etherdelta/smart_contract And just i used remix.ethereum to build it What i’m doing wrong? In this works in the other contract created by the creator You…