go // the folder main.go // file 1 block.go // file 2

// use the main packagepackage main//import the fmt packageimport ("fmt")func main(){fmt.Println("I am building my first blockchain") // print thisCreateBlock("The hearder will be shown here", "the body will be shown here") // call the function that will create the block and pass some parameters in it.}

package mainimport ("fmt" // this will help us to print on the screen)func CreateBlock(Header, Body string){fmt.Println(Header ,"\n", Body) // Show me the block content}

package main //Import the main package// Create the Block data structure// A block contains this info:type Block struct { Timestamp int64 // the time when the block was created PreviousBlockHash []byte // the hash of the previous block MyBlockHash []byte // the hash of the current block AllData []byte // the data or transactions (body info)}
// Prepare the Blockchain data structure :type Blockchain struct { Blocks []*Block // remember a blockchain is a series of blocks}

package main
import ( // We will need these libraries: "bytes" // need to convert data into byte in order to be sent on the network, computer understands better the byte(8bits)language "crypto/sha256" //crypto library to hash the data "strconv" // for conversion "time" // the time for our timestamp)
// Now let's create a method for generating a hash of the block// We will just concatenate all the data and hash it to obtain the block hashfunc (block *Block) SetHash() { timestamp := []byte(strconv.FormatInt(block.Timestamp, 10)) // get the time and convert it into a unique series of digits headers := bytes.Join([][]byte{timestamp, block.PreviousBlockHash, block.AllData}, []byte{}) // concatenate all the block data hash := sha256.Sum256(headers) // hash the whole thing block.MyBlockHash = hash[:] // now set the hash of the block}
// Create a function for new block generation and return that blockfunc NewBlock(data string, prevBlockHash []byte) *Block { block := &Block{time.Now().Unix(), prevBlockHash, []byte{}, []byte(data)} // the block is received block.SetHash() // the block is hashed return block // the block is returned with all the information in it}
/* let's now create the genesis block function that will return the first block. The genesis block is the first block on the chain */func NewGenesisBlock() *Block { return NewBlock("Genesis Block", []byte{}) // the genesis block is made with some data in it}

package main
// create the method that adds a new block to a blockchainfunc (blockchain *Blockchain) AddBlock(data string) { PreviousBlock := blockchain.Blocks[len(blockchain.Blocks)-1] // the previous block is needed, so let's get it newBlock := NewBlock(data, PreviousBlock.MyBlockHash) // create a new block containing the data and the hash of the previous block blockchain.Blocks = append(blockchain.Blocks, newBlock) // add that block to the chain to create a chain of blocks}
/* Create the function that returns the whole blockchain and add the genesis to it first. the genesis block is the first ever mined block, so let's create a function that will return it since it does not exist yet */func NewBlockchain() *Blockchain { // the function is created return &Blockchain{[]*Block{NewGenesisBlock()}} // the genesis block is added first to the chain}

//Time to put everything together and testpackage mainimport ( "fmt" // just for printing something on the screen)func main() { newblockchain := NewBlockchain() // Initialize the blockchain // create 2 blocks and add 2 transactions newblockchain.AddBlock("first transaction") // first block containing one tx newblockchain.AddBlock("Second transaction") // second block containing one tx // Now print all the blocks and their contents for _, block := range newblockchain.Blocks { // iterate on each block fmt.Printf("Hash of the block %x\n", block.MyBlockHash) // print the hash of the block fmt.Printf("Hash of the previous Block: %x\n", block.PreviousBlockHash) // print the hash of the previous block fmt.Printf("All the transactions: %s\n", block.AllData) // print the transactions } // our blockchain will be printed}

fmt.Printf("Block ID : %d \n", i) fmt.Printf("Timestamp : %d \n", block.Timestamp+int64(i))

//Time to put everything together and testpackage main
import ( "fmt" // just for printing something on the screen)
func main() { newblockchain := NewBlockchain() // Initialize the blockchain // create 2 blocks and add 2 transactions newblockchain.AddBlock("first transaction") // first block containing one tx newblockchain.AddBlock("Second transaction") // second block containing one tx // Now print all the blocks and their contents for i, block := range newblockchain.Blocks { // iterate on each block fmt.Printf("Block ID : %d \n", i) // print the block ID fmt.Printf("Timestamp : %d \n", block.Timestamp+int64(i)) // print the timestamp of the block, to make them different, we just add a value i fmt.Printf("Hash of the block : %x\n", block.MyBlockHash) // print the hash of the block fmt.Printf("Hash of the previous Block : %x\n", block.PreviousBlockHash) // print the hash of the previous block fmt.Printf("All the transactions : %s\n", block.AllData) // print the transactions } // our blockchain will be printed}