How to upgrade the Ethereum smart contract
At present, there are many channels for domestic users to buy Ethereum. Here are some common channels:
< H2 > 1. Coincola is an over-the-counter trading platform for indivials to trade bitcoincoy Cola is affiliated to Hong Kong coincola limited, which is developed and operated by a professional international team, focusing on providing convenient and reliable blockchain services for global users. Coincola gathers global users and is committed to building a world-class blockchain asset platform
in coy cola, people from different countries can buy bitcoin with their own currency. The seller of the website publishes the advertisement of selling bitcoin, and explains the payment method and exchange rate. You can choose to trade directly online according to the content of the advertisement. Bitcoin is stored in Ke Ying Cola's Internet wallet. You can transfer bitcoin directly
2. How to buy eth
register the coincola account, and then click "buy" in the top menu of the home page to enter the advertisement list page
select the appropriate advertisement from the advertisement list and click "buy eth" to enter the transaction page
enter the amount of money to be purchased or the number of digital currency (please understand the message information of the other party, payment method, and transaction instructions of the platform before entering), click buy now, and the order confirmation pop up. After checking and confirming the information, click confirm purchase to enter the order page
in the chat box of the platform, you can inquire whether the other party is online according to the template statement, and make offline payment according to the collection information and collection method provided by the other party
after the completion of offline payment, click the mark that the payment has been completed at the first time (please complete this operation within 15 minutes at the beginning of placing an order, so as to avoid the payment cannot be recovered e to the cancellation of the order e to overtime), and then customize the input information in the chat box to confirm the payment and ask the seller to confirm the collection and release the digital currency
the progress bar in the top column shows that the goods have been received, indicating that the digital currency has arrived in the wallet. Make comments according to the seller's behavior, and click submit to complete the transaction
with the rapid increase in the number of trading platforms and competitive pressure, many trading platforms will have their own C2C trading. Here we take the relatively large ZB trading platform as an example to illustrate
What is C2C
C2C transaction is a customer to customer transaction, which is guaranteed by the transaction platform. There are many such platforms, such as: Fire coin, otcbtc, bitpai OTC, etc., which are guaranteed by the platform and traded between users. We can simply understand it as: our shopping situation on Taobao is the same as that. In case of dispute, the platform will arbitrate. As long as the transaction is carried out according to the normal process, the security of the transaction is guaranteed
2. ZB's C2C business
ZB platform has two choices: QC and usdt. The basic logic is the same. There are many usdt platforms. QC is the feature of ZB, EXX and other platforms. Here we focus on QC
< H2 > about QCQC is a token. At present, you may know more about usdt and bitcny. At present, there is a special area for QC transaction on ZB. Simply put, QC can buy all other digital currencies (BTC, ETH, EOS, etc.) on ZB. Therefore, after purchasing QC with RMB recharge, you can conct currency transaction on ZB station
The advantage of the < H2 > QC token is that the exchange ratio between the < H2 > < UL >and RMB is 1:1, which is easier to convert
purchasing other tokens with QC can be directly understood as purchasing RMB, and has an intuitive understanding of the currency price
it takes about half an hour to get to the account. It will take about two hours to get to the account in congestion
ZB platform is relatively reliable, and the reputation of ZB is still very good in the past
How to operate C2C of ZB < UL >log in to ZB trading platform and click "C2C trading" on the page
to get to the QC transaction page, you need to first bind your bank card. Then, in the buy QC interface, enter the quantity of QC you want to buy. At present, the ratio of QC to RMB is 1:1. Enter the purchase quantity and click "buy now"
after clicking "buy now", you will be prompted to complete the payment within 30 minutes. At the same time, payment information is generated. Please note that the payment must be made according to the prompt
business processing time 9:00-21:00. Non processing time orders will be processed at 9:00 the next day, and the payment will be completed within 24 hours after receiving the order
this means that the merchant you paid will transfer QC coin to your account within 24 hours. According to my experience, you can get to the account in 2 hours ring the day
< H2 > the following points should be paid attention to:1) make sure to use the newly bound bank card for transfer and payment
2) note information (that 6 digit) must fill in
3) do not use Alipay, WeChat and other transfers. p>
4) do not fill in the opposite account incorrectly
< UL >about 1-2 hours, you can check whether your QC has arrived in the financial center
after the account is received, you can trade in the "QC" zone of the "spot trading". You can choose the transaction you want to buy and buy the order
Thank you for your recommendation. Here I would like to share with you the following:
forsage international crowdfunding, the revolutionary smart contract technology of the new generation platform, originated from the development of Russian technical team, provides distributed market participants with the ability to directly engage in personal and commercial transactions. The smart contract of forsage distributed global shared matrix project is open and can always be viewed on the Ethereum blockchain. These are real smart contracts, which will be implemented on the Ethereum public chain forever without any third party tampering. The global shared matrix project is completely decentralized, aiming to preach Ethereum, so that more players can know Ethereum, smart contracts and forsage code btshijie
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
the Ethereum project has a bigger goal. As Ethereum said, "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 smart contract
smart contracts are applications that run on Ethereum virtual machines. This is a distributed "world computer" with computing power provided by all Ethereum nodes. Any node providing computing power will pay in ether digital currency as a resource
they are named smart contracts because you can write "contracts" that execute automatically when you meet the requirements
for example, imagine building a KickStarter like crowdfunding service on Ethereum. Someone can set up an Ethereum smart contract to pool funds to others. The smart contract can be written as follows: when $100000 of currency is added to the pool, it will be sent to the recipient. Or, if the $100000 threshold is not reached within a month, all currencies will be returned to the original holder of the currency. Of course, this would use ether instead of dollars
all this will be done according to the smart contract code, which can automatically execute the transaction without the need for a trusted third party to hold the currency and sign the transaction. For example, KickStarter charges 5% above the 5% payment processing fee, which means it will charge $8000 to $10000 for a $100000 crowdfunding project. Smart contracts don't have to pay a fee to a third party like KickStarter
smart contracts can be used for many different things. Developers can create smart contracts to provide functions for other smart contracts, similar to the way software libraries work. Alternatively, smart contracts can simply be used as applications to store information on the Ethereum blockchain
in order to really execute the smart contract code, someone has to send enough Ethernet tokens as the transaction fee - how much depends on the required computing resources. This costs the Ethereum nodes to participate and provide computing power. The global shared matrix project, which is completely decentralized, aims to preach Ethereum and let more players know Ethereum, smart contracts and forsage code btshijie
& quot; A smart contract is a set of promises defined in digital form, including the agreements on which the contract participants can execute these promises& quot;
let's explore the meaning of his definition in more detail
commitment
a set of commitments refers to the (often mutual) rights and obligations agreed by contract participants. These commitments define the nature and purpose of the contract. Take a sales contract as a typical example. The seller promises to deliver the goods and the buyer promises to pay a reasonable price
digital form
digital form means that contracts have to be written into computer-readable code. This is necessary, because as long as the participants reach an agreement, the rights and obligations of smart contract establishment are executed by a computer or computer network
to further explain:
(1) when will the parties to the smart contract reach an agreement? The answer depends on the specific smart contract implementation. Generally speaking, the contract is discovered when the parties are committed to the execution of the contract by installing the contract on the contract host platform< (2) contract execution
& quot; Execute & quot; And the real meaning of it also depends on implementation. Generally speaking, implementation means active implementation through technical means
(3) computer readable code
in addition, the contract needs specific & quot; Digital form & quot; Very much depends on the agreement that the parties agree to use
protocol
protocol is technical implementation, on this basis, the contract commitment is realized, or the contract commitment is recorded. Which agreement to choose depends on many factors, the most important of which is the nature of the assets being traded ring the performance of the contract
take the sales contract as an example. Suppose that the participants agree to pay in bitcoin. The chosen protocol will obviously be bitcoin protocol, on which the smart contract will be implemented. Therefore, the contract must use & quot; Digital form & quot; It's bitcoin scripting language. Bitcoin scripting language is a non Turing complete, imperative, stack based programming language, similar to forth.
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
a total of 22 weeks, divided into five stages,
the first stage is 4 weeks, go language foundation and network concurrency, learning the introctory go language,
the second stage is 4 weeks, go language practical web development, crawler development, cryptography, consensus algorithm, realizing lightweight public chain, learning the website and crawler that can develop golang, Achieve lightweight blockchain
stage 3, 4-week Ethereum source code analysis and smart contract DAPP development, master Ethereum core and smart contract development, as well as blockchain,
stage 4, 4-week super ledger, bitcoin EOS, source code analysis and smart contract practice, master super ledger development, cat bitcoin, bifurcated EOS after learning, As well as DAPP development of smart contract
phase 5, 6-week project practice, five enterprise level projects, and one year of blockchain project experience after learning
from the characteristics of the language itself, go is a very efficient language, which highly supports concurrency. Go language itself pays more attention to distributed system, and concurrency processing is relatively good, such as advertising and search, That kind of high concurrency server
go language advantages:
excellent performance, can be directly compiled into machine code, does not rely on other libraries, go is extremely fast. Its performance is similar to Java or C + +
concurrency is supported at the language level, which is the biggest feature of go. It is born to support concurrency, and go is the concurrency supported in gene, which can make full use of multi-core and make it easy to use concurrency
the built-in runtime supports garbage collection, which is one of the features of dynamic language. Although GC is not perfect at present, it is enough to cope with most of the situations we can encounter, especially GC after go1.1
it's easy to learn. The authors of go language all have the gene of C, so go naturally has the gene of C. There are 25 go keywords, but the expressive ability is very strong. It almost supports most of the features you've seen in other languages: inheritance, overloading, object, etc
rich standard libraries, go has built a large number of libraries, especially the network library, which is also my favorite part< As like as two peas, br / > built-in powerful tools, Go language is built with many tools chain, the best should be gofmt tools, automatic formatting code, make team review become so simple, code format is exactly the same, it is very difficult to think differently.
cross platform compilation and fast compilation. Compared with the sluggish compilation speed of Java and C + +, the fast compilation time of go is a major efficiency advantage
disadvantages of go language:
package management: package management of go language is absolutely not perfect. By default, it has no way to make a specific version of the dependency library, nor can it create replicable builds. In contrast, python, node and Ruby all have better package management systems. However, with the right tools, the package management of go language can also perform well
lack of development framework: go language does not have a major framework, such as Ruby's rails framework, Python's Django framework or PHP's laravel. This is a heated discussion in the go language community, because many people think that we should not start with using frameworks. This is true in many cases, but if you just want to build a simple crud API, it's much easier to use Django / djrf, rails laravel, or Phoenix
exception handling: go language can help developers deal with compilation errors by simply returning errors (or call stack) through functions and expected calling codes. Although this method is effective, it is easy to lose the scope of the error, so it is difficult to provide meaningful error information to users. Error package can solve this problem by allowing us to add context and stack trace to return error
another problem is that we may forget to handle errors. Static analysis tools such as errcheck and megacheck can avoid these errors. Although these solutions are very effective, they may not be the right way.
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
Generally speaking, the steps of deploying smart contract are as follows:
- start an Ethereum node (such as geth or testrpc)
- use Solc to compile smart contracts=& gt; Get the binary code
- deploy the compiled contract to the network This step will consume Ethernet currency, and you need to use the default address or specified address of your node to sign the contract.)=& gt; Get the blockchain address and ABI of the contract (JSON representation of the contract interface, including variables, events and callable methods) The author confused ABI with contract interface here. ABI is the binary representation of the contract interface.)
- use the JavaScript API provided by web3.js to call the contract Depending on the type of call, it may consume Ethernet currency.)