Hello Folks,

So in this session we will be discussing about converting a negative number to two's compliment using web3 from nodejs.

To do that we need to have web3 Node module installed on our system.

We can do this by running the following code on the cmd

npm install web3

Then let's run our node server. Just run the following code on cmd.

node

Then we need web3 module in our server so run the following code

var Web3 = require('web3')

we will be needing a Blockchain network to create an account  so get an rpc url from here

Just click on the link -> Login to your account ->Click on ethereum on left side bar ->create project ->settings->keys->endpoints 

and choose your respective testnet rpc url

rpc url it will look like this - https://kovan.infura.io/v3/your_api_key

 var url = 'your RPC url here'

Then run this one

var web3 = new Web3(url)

To convert a negative numer into a two’s complement; we can use this utility function

Basic Syntax:

web3.utils.toTwosComplement(number)

This will return the converted hex string value

Example:

web3.utils.toTwosComplement('-1');
> "0xffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffff"     //output

web3.utils.toTwosComplement(-1);
> "0xffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffff"     //output

web3.utils.toTwosComplement('0x1');
> "0x0000000000000000000000000000000000000000000000000000000000000001"     //output

web3.utils.toTwosComplement(-15);
> "0xfffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffff1"    //output

web3.utils.toTwosComplement('-0x1');
> "0xffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffff"     //output

 So that's all for today's session.

For test ethers and link tokens. Click Here

For many more exciting tutorials keep following my username @BlockTalks_Raj

!!!!!HAPPY LEARNING!!!!