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packageblockchain

​

import(

"crypto/sha256"

"fmt"

"sync"

)

​

typeblockstruct{

data string

hash string

prevHash string

}

​

typeblockchainstruct{

blocks []*block

}

​

var b *blockchain

var once sync.Once

​

func(b *block)calculateHash(){

hash := sha256.Sum256([]byte(b.data + b.prevHash))

b.hash = fmt.Sprintf("%x", hash)

}

​

funcgetLastHash()string{

totalBlocks :=len(GetblockChain().blocks)

if totalBlocks ==0{

return""

}

returnGetblockChain().blocks[len(totalBlocks)-1].hash

}

​

funccreateBlock(data string)*block {

newBlock := block{data,"",getLastHash()}

newBlock.calculateHash()

return&newBlock

}

​

funcGetblockChain()*blockchain {

if b ==nil{

once.Do(func(){

b =&blockchain{}

b.blocks =append(b.blocks,createBlock("Genesis Block"))

})

}

return b

}

​