How to store data in Ethereum

1. You can choose to trade in the digital currency exchange. At present, the mainstream digital currency exchanges in the market are coin security, fire currency and bitnet.

2. No, it only needs the currency supported by the wallet. If the currency not supported by the wallet is transferred in, the coin will be lost. The charging address of each coin is different. Moreover, the wallet is a small platform. I feel that it is not as safe as ZB, but some personal wallets can be used with some amount

3.

If you want to query the transaction records on the main network, you can use Etherscan. However, if you build your own private chain, how should you query the transaction records

the answer is that you need to listen to the logs on the chain, save them in the database, and then query them in the database. For example:

< pre t = "code" L = "Java" > varaddr = & quot& quot;< br />varfilter=web3.eth.filter({fromB lock:0 ,toBlock:' latest', address:addr });< br />filter.get(function(err,transactions){
transactions.forEach(function(tx){
vartxInfo=web3.eth.getTransaction(tx.transactionHash);
/ / at this time, the transaction information txinfo can be stored in the database
})< br />});

Web3. Eth. Filter() is used to monitor the log on the chain, and Web3. Eth. Gettransaction() is used to extract the information of the specified transaction. Once the transaction information is obtained, it can be stored in the database for query

recommend a practical introction, you can see: Ethereum tutorial

4. Coin security and Ethereum perform their respective ties. They can't include all the functions and technologies. They are proficient in all the features. If they want the instry to move forward better, they must make common progress.

5. Hello
first of all, you need to have an Ethernet wallet account number and address. Then you can display the currency in your personal assets or personal account on the trading platform. Click Ethereum to withdraw the currency and fill in the address of your wallet
Mr. Yuan Wang is engaged in the development of digital asset blockchain system. If you need to develop it, you can search "Mr. Yuan Wang" on the Internet for detailed communication

6. Has the economy made up for the saturation of single mines, and has the military buildings made up for it? 4bg generally 20 farmers, 4 sent troops to build brush troops. T farmers must not stop making up until the single mine is saturated, at least 3BB ~ 4BB should keep sending troops, and should not link up science and technology early at the same time, which will lead to the decline of barracks proction

t if there is no need for underground protection in a single mine, there is no problem in directly attacking 4bg, and science and technology will not lag behind. I have to bear the pressure. I can't forget many details when I was harassed by others in the early stage. How to fight or how to fight

take be down in 7 minutes. When the time is up, there will be an air defense in the mining area. This is a discipline. Unless you have a clear detection that the opposite side is not a hidden knife, otherwise this must be done

you open mine 2, but there is no mine 2 on the opposite side. The first thing in your mind is to defend mine 2 and fight to death. Do you still have time for Dahe? I think too much

7. In go, the outcome is determined by the number of intersections. The intersection is the result of the intersection of 19 horizontal lines and 19 vertical lines in the chessboard × 19 = 361 points. In technical terms, these points are called "Mu" or "Zi". The last side with more mesh or sub number wins. But generally speaking, the black side should first paste 7.5 mesh to the white side to balance the advantages of the first hand, that is to say, the white side should add 7.5 mesh to compare with the black side. Note that the meanings of "Mu" and "Zi" are different from those mentioned above. Here, "Mu" and "Zi" refer to two different methods of calculating the outcome. Either method can be used, and the meaning is the same

let's first talk about the calculation method of "item": the difference between the number of items on both sides, such as 180.5 items on the black side and 180.5 items on the white side, is that the white side wins 7.5 items, because the black side has to post 7.5 items first

let's talk about the calculation method of "sub": half of the intersection point is 180.5 + 3 + 3 / 4 (half of 7.5 mesh). If one party wins by more than this number, the number of sub winning is the difference between the number of sub winning party and 180.5 + 3 + 3 / 4, which is the same as the above example, that is, white party wins 3 + 3 / 4.

8. According to the meaning of the% sign, what's the percentage in 100 points?
if it's 1%, does it mean that the handling charge of 100 yuan is 1 yuan

9.

Transaction

the behavior of blockchain transaction follows different rule sets

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e to the distributed and unlicensed nature of public blockchain, anyone can sign the transaction and broadcast it to the network

according to different blockchains, traders will be charged a certain transaction fee, which depends on the needs of users rather than the value of assets in the transaction

blockchain transactions do not require any central authority verification. It only needs to use the digital signature algorithm (DSA) corresponding to its blockchain to sign it with the private key

once a transaction is signed, broadcast to the network and mined into a successful block in the network, the transaction cannot be recovered

Ethereum transaction structure

Ethereum transaction data structure: transaction 0.1 eth

{
& 39; nonce':&# 39; 0x00', // Decimal: 0
& 39; gasLimit': &# 39; 0x5208', // Decimal system: 21000
& 39; gasPrice': &# 39; 0x3b9aca00', // Decimal system: 10000000000
& 39; to': &# 39;&# 39; ，// Sending address
& 39; value': &# 39; 0x16345785d8a0000',// 100000000000000000 ，10^17
' data': &# 39; 0x', // Decimal representation of null data; chainId': 1 / / blockchain network ID
}

these data have nothing to do with the transaction content, but have something to do with the execution mode of the transaction. This is because when you send a transaction in Ethereum, you must define some other parameters to tell miners how to handle your transaction. Transaction data structure has two attribute designs & quot; gas": & quot; gasPrice",& quot; gasLimit"

" gasPrice": The unit is Gwei, which is 1 / 1000 eth, indicating the transaction cost

& quot; gasLimit": The maximum gas charge allowed for the transaction

these two values are usually filled in automatically by the wallet provider

in addition, you need to specify which Ethereum network to execute the transaction (chainid): 1 represents the Ethereum main network

ring development, tests are usually carried out locally and on the test network, and transactions are carried out through the test eth issued by the test network to avoid economic losses. After the test, enter the main network transaction

in addition, if you need to submit some other data, you can use & quot; data" And & quot; nonce" Attach as part of a transaction

a nonce (number used only once) is the value used by Ethereum to track transactions, which helps to avoid double spending and replay attacks in the network

Ethereum transaction signature

Ethereum transaction involves ECDSA algorithm. Taking JavaScript code as an example, the popular ethers.js is used to call ECDSA algorithm for transaction signature

const ethers = require(' ethers')

const signer = new ethers.Wallet(' Wallet address

signer.signTransaction({

' nonce':&# 39; 0x00', // Decimal: 0

& 39; gasLimit': &# 39; 0x5208', // Decimal: 21000

& 39; gasPrice': &# 39; 0x3b9aca00', // Decimal 10000000000

& 39; to': &# 39;&# 39; ，// Sending address

& 39; value': &# 39; 0x16345785d8a0000',// 100000000000000000 ，10^17

' data': &# 39; 0x', // Decimal representation of null data

& 39; chainId': 1 / / blockchain network ID

})

. Then (console. Log)

you can use the online application composer to deliver signed transactions to Ethereum. This is known as "offline signature.". Offline signatures are particularly useful for applications such as status channels, which are smart contracts that track the balance between two accounts and transfer funds after a signed transaction is submitted. Offline signature is also a common practice in dexes

you can also use online wallet to create signature verification and broadcast through Ethereum account

with Portis, you can sign a transaction to interact with the gas station network (GSN)

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