Ethereum precompile contract
Publish: 2021-04-25 17:05:32
1. Ethereum is a new and open blockchain platform, which allows anyone to build and use decentralized applications running through blockchain technology in the platform
just like bitcoin, Ethereum is neither controlled nor owned by anyone - it is an open source project created by many people around the world. Different from bitcoin protocol, Ethereum's design is very flexible and adaptable. It is very easy to create new applications on the Ethereum platform. With the release of homestead, anyone can use the applications on this platform safely
Ethereum is a programmable blockchain. It does not give users a series of preset operations, but allows users to create complex operations according to their own wishes. In this way, it can be used as a platform for many types of decentralized blockchain applications
in a narrow sense, Ethereum refers to a series of protocols that define a decentralized application platform. The core of Ethereum is Ethereum virtual machine (EVM), which can encode any complex algorithm. In computer science terminology, Ethereum is "Turing complete.". Developers can use the existing JavaScript and python as the model of other friendly programming languages to create applications running on the Ethereum simulator.
just like bitcoin, Ethereum is neither controlled nor owned by anyone - it is an open source project created by many people around the world. Different from bitcoin protocol, Ethereum's design is very flexible and adaptable. It is very easy to create new applications on the Ethereum platform. With the release of homestead, anyone can use the applications on this platform safely
Ethereum is a programmable blockchain. It does not give users a series of preset operations, but allows users to create complex operations according to their own wishes. In this way, it can be used as a platform for many types of decentralized blockchain applications
in a narrow sense, Ethereum refers to a series of protocols that define a decentralized application platform. The core of Ethereum is Ethereum virtual machine (EVM), which can encode any complex algorithm. In computer science terminology, Ethereum is "Turing complete.". Developers can use the existing JavaScript and python as the model of other friendly programming languages to create applications running on the Ethereum simulator.
2.
The smart contract has been written for a long time
if they can add changes, the description is centralized
the contract is written into the Ethereum smart contract, which is a contradiction sentence
the financial customer service doesn't understand, which is very unreliable
community sites
3. Gas & gt; ethestimateGas({ from:ethaccounts [1], to: ethaccounts[2], value:50000000000000 }) 21001 > Ethgasprice 2000000000, as shown above, shows this account [1] = & gt; The transaction of account [2] needs 21001 gas, and the current gasprice is 2000000000. How many gas does it take to send transaction / call contract method in Ethereum
4. Ethereum is a distributed computing platform. It generates an cryptocurrency called ether. Programmers can write "smart contracts" on the Ethereum blockchain, and these Ethereum smart contracts will be executed automatically according to the code
what is Ethereum
Ethereum is often compared with bitcoin, but the situation is different. Bitcoin is a kind of cryptocurrency and distributed payment network, which allows bitcoin to be transferred between users
related: what is bitcoin? How does it work
Ethereum has a bigger goal. As Ethereum says, "Ethereum is a distributed platform running smart contracts.". These smart contracts run on "Ethereum virtual machine", a distributed computing network composed of all devices running Ethernet nodes
"distributed platform" means that anyone can set up and run an Ethereum node just as anyone can run a bitcoin node. Anyone who wants to run "smart contracts" on nodes must pay the operators of these nodes in ether, which is a cryptocurrency related to Ethereum. Therefore, the person running the Ethernet node provides computing power and gets paid in the Ethernet, which is similar to the way that the person running the bitcoin node provides hash power and pays in bitcoin
in other words, although bitcoin is only a blockchain and payment network, Ethereum is a distributed computing network, and its blockchain can be used for many other things. Details are provided in the Ethereum white paper
what is ether
Ethernet is a digital token (or cryptocurrency) related to Ethereum blockchain. In other words, Ethereum is the token and Ethereum is the platform. But now people often use these terms alternately. For example, coinbase allows you to buy Ethereum, which stands for Ethereum
this is technically "altcoin", which actually means a non bitcoin cryptocurrency. Like bitcoin, ether is supported by distributed blockchain - in this case, Ethereum blockchain
developers who want to create applications or Ethereum smart contracts on Ethereum blockchain need Ethernet token to pay for nodes to host it, while users of Ethereum based applications may need Ethernet to pay for services in these applications. People can also sell services outside the Ethereum network and accept Ethernet payments, or they can sell Ethernet tokens in cash - just like bitcoin
what is Ethereum
Ethereum is often compared with bitcoin, but the situation is different. Bitcoin is a kind of cryptocurrency and distributed payment network, which allows bitcoin to be transferred between users
related: what is bitcoin? How does it work
Ethereum has a bigger goal. As Ethereum says, "Ethereum is a distributed platform running smart contracts.". These smart contracts run on "Ethereum virtual machine", a distributed computing network composed of all devices running Ethernet nodes
"distributed platform" means that anyone can set up and run an Ethereum node just as anyone can run a bitcoin node. Anyone who wants to run "smart contracts" on nodes must pay the operators of these nodes in ether, which is a cryptocurrency related to Ethereum. Therefore, the person running the Ethernet node provides computing power and gets paid in the Ethernet, which is similar to the way that the person running the bitcoin node provides hash power and pays in bitcoin
in other words, although bitcoin is only a blockchain and payment network, Ethereum is a distributed computing network, and its blockchain can be used for many other things. Details are provided in the Ethereum white paper
what is ether
Ethernet is a digital token (or cryptocurrency) related to Ethereum blockchain. In other words, Ethereum is the token and Ethereum is the platform. But now people often use these terms alternately. For example, coinbase allows you to buy Ethereum, which stands for Ethereum
this is technically "altcoin", which actually means a non bitcoin cryptocurrency. Like bitcoin, ether is supported by distributed blockchain - in this case, Ethereum blockchain
developers who want to create applications or Ethereum smart contracts on Ethereum blockchain need Ethernet token to pay for nodes to host it, while users of Ethereum based applications may need Ethernet to pay for services in these applications. People can also sell services outside the Ethereum network and accept Ethernet payments, or they can sell Ethernet tokens in cash - just like bitcoin
5.
Yes, refer to the interaction between contracts. Digital currency exchange platform for example, I am trying to sign a smart contract from another factory contract and then redeploy the address of the new smart contract. However, the address it returns is the transaction hash, not the contract address. I believe this is because when the address is returned, the contract has not been exploited. When I deploy the smart contract with Web3, it seems that it will not output the contract address until the smart contract is deployed
6. Contract code of Ethereum. If the WPS document is used to analyze the , it's not clear.
I haven't touched it
I haven't touched it
7. In solidness, a contract consists of a set of code (contract function) and data (contract state). The contract is located at a special address on the Ethereum blockchain. uint storedData; This line of code declares a state variable, named storeddata, of type uint (256 bits unsigned integer). You can think of it as a storage unit in a database. Just like managing a database, you can query and modify it by calling functions. In Ethereum, usually only the owner of the contract can do so. In this example, the functions set and get are used to modify and query the values of variables, respectively
like many other languages, when accessing state variables, it is not necessary to add a prefix such as this
this contract can't do a lot (limited by Ethereum's infrastructure), it just allows anyone to store a number. And anyone in the world can access this number. There is no reliable way to protect the number you publish. Anyone can call the set method to set a different number to cover your published number. But your numbers will remain in the history of blockchain. Later we'll learn how to add an access limit so that only you can change the number
token example
the next contract will implement a cryptocurrency in the simplest form. Taking money in the air is no longer a magic trick. Of course, only the person who creates the contract can do it (it's also very easy to use other currency issuance modes, just to realize the differences in details). And anyone can send money to others, without registering a user name and password, as long as there is a pair of Ethereum public and private keys
note
this is not a good example for online solidness environments. If you use the online solidity environment to try this example. The address of from cannot be changed when the function is called. So you can only play the role of a coiner, you can cast money and send it to others, but you can't play the role of others. This online solidity environment will be improved in the future.
like many other languages, when accessing state variables, it is not necessary to add a prefix such as this
this contract can't do a lot (limited by Ethereum's infrastructure), it just allows anyone to store a number. And anyone in the world can access this number. There is no reliable way to protect the number you publish. Anyone can call the set method to set a different number to cover your published number. But your numbers will remain in the history of blockchain. Later we'll learn how to add an access limit so that only you can change the number
token example
the next contract will implement a cryptocurrency in the simplest form. Taking money in the air is no longer a magic trick. Of course, only the person who creates the contract can do it (it's also very easy to use other currency issuance modes, just to realize the differences in details). And anyone can send money to others, without registering a user name and password, as long as there is a pair of Ethereum public and private keys
note
this is not a good example for online solidness environments. If you use the online solidity environment to try this example. The address of from cannot be changed when the function is called. So you can only play the role of a coiner, you can cast money and send it to others, but you can't play the role of others. This online solidity environment will be improved in the future.
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