Ethereum support language

1. Go full stack + blockchain course:
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.

2.

Ethereum is an open source public blockchain platform with smart contract function. It provides decentralized virtual machine (Ethereum virtual machine) to process point-to-point contract through its special cryptocurrency ether (also known as "Ethereum")

The token on the

blockchain is called ether, and the code is eth. It can be traded in many foreign exchange markets of cryptocurrency, and it is also the medium used to pay transaction fees and computing services on Ethereum

the concept of Ethereum was first proposed by vitalik buterin, a programmer, from 2013 to 2014, inspired by bitcoin, with the general meaning of "next generation cryptocurrency and decentralized application platform", and began to develop through ICO crowdfunding in 2014. As of February 2018, Ethernet is the second highest cryptocurrency in market value, second only to bitcoin

extended data:

Ethereum platform has no characteristics and value. Like programming languages, it's up to entrepreneurs and developers to decide what to use. However, it is clear that some application types benefit more from the functions of Ethereum than others. Ethereum is especially suitable for those applications that automatically interact directly between points or promote group coordination activities across networks

for example, coordinate the application of point-to-point market, or the automation of complex financial contracts. Bitcoin enables indivials to exchange money without the help of financial institutions, banks or governments. The impact of Ethereum may be more profound

in theory, any complex financial activities or transactions can be automatically and reliably carried out on Ethereum with coding. In addition to financial applications, any application scenario with high requirements for trust, security and persistence, such as asset registration, voting, management and Internet of things, will be affected by Ethereum platform on a large scale

3.

1. about the variability of blockchain

2. eth, if most people agree to modify the chain, that is, variability, then they can modify the blockchain records and contracts

3. etc, blockchain records and contracts can't be modified, that is, they can't be tampered with

4. here are the advantages and disadvantages of the two methods

   The advantage of

5. variability is that people can make timely changes to make the right decisions. Therefore, modifying the specification is more practical than finding loopholes

6. non modifiability means that no matter how smart people are at that time, it is impossible not to make mistakes. Therefore, when problems arise in this scheme, it is best to find and solve the loopholes through the existing legal framework

7. differences in development

8. eth, whether it is intentionally arranged or since its birth, the core decisions of blockchain are made by Ethereum foundation with the participation of the community and most of them are developed by it

9. etc, the decision-making of blockchain is mainly decided by the feedback of three loose, collaborative teams with community participation

10. in any case, anyone can put forward improvement suggestions for the two kinds of blockchains. This is the benefit of open source, and it is also very common. You will find that developers of the two chains communicate with each other through GitHub and reddit. I hope to improve the frequency of communication in order to achieve the common goal

11. about compatibility

12. at present, the two kinds of blockchains are compatible with each other. Contracts or applications written by eth can be applied on etc, and vice versa

13. eth, focusing on ewasm, is committed to providing a platform for more and more developers, while the issue of contract security is secondary, such as viper

14. etc focuses on making developers create more secure contracts, such as viper, iohk research, at the cost of consuming the number of potential developers

15. it's obvious that both chains can accept each other, regardless of whether their wishes are the same or not. My view is that the number of developers is not necessarily related to the quality of the proct

16. about the transaction speed

17. eth, the average is 25 seconds, which will be shortened after upgrading

18. etc, with an average time of 14 seconds, maintained at 10-14 seconds after upgrade, according to ecip-1010 and ecip-1036 protocols

19. about the block capacity

20. eth, with the daily trading volume of eth graally reaching 5 million, the block capacity is graally saturated. This situation is similar to the recent transaction cost of bitcoin. This problem can be solved by expanding the block capacity by increasing the default fuel limit

21. ETC­， At present, there is still a lot of room for block capacity. As more and more people accept etc, the block capacity will also increase, just like eth

22. about community

23. eth, mainly discuss on reddit

24. etc, mainly discuss on slack

25. about monetary policy

26. eth, the planned supply is growing steadily, resulting in an average inflation of 3% in eth blockchain in its life cycle

27. etc, before 2025, inflation will reach 3%, and then the total supply will reach 200 million etc, and then there will be deflation

    As for the regional distribution of trading volume, China accounts for 20%, South Korea 25% and the United States 25%
    In etc, China accounts for 50%, South Korea 25% and the United States 10%
    About securities, at present, investors do not have the option to trade securities. Recently, one of eth's ETFs, trading open-end index funds, was denied by the regulators

28. etc owns etc trading trust, which allows investors to own etc instead of the asset itself

4. Ethereum is an open source public blockchain platform with smart contract function. It provides decentralized virtual machine (Ethereum virtual machine) to process point-to-point contract through its special cryptocurrency ether (also known as "Ethereum"). The concept of Ethereum was first proposed by vitalik buterin, a programmer, from 2013 to 2014, inspired by bitcoin, to the effect of "next generation cryptocurrency and decentralized application platform". It began to develop through ICO crowdfunding in 2014
Ethereum is not only a database, it also allows you to run programs in the trusted environment of the blockchain. Ethereum has built a virtual machine named EVM (Ethereum virtual machine) on the blockchain. EVM allows code to be verified and executed on the blockchain, providing guarantee for code to run in the same way on everyone's machine. These codes are included in the smart contract. In addition to tracking the account balance, Ethereum uses the same method to save the EVM status on the blockchain. All nodes process the smart contract to verify the integrity of the contract itself and its output.

5. Go language is the mainstream language of blockchain
according to the data survey of boss Research Institute, go and C + + are the mainstream languages of blockchain Posts currently recruited. The early blockchain system and application
programs are mainly implemented in C + +, and now most companies will use go language to
build public chain systems<
C + + is suitable for the development of local programs.
go language is suitable for the development of network programs and local programs.
compared with C + + go, it has the following advantages:
garbage collection
clear meaning
unified format

disadvantages:
efficiency is not as high as C + + at present, but for desktop programs, efficiency is not a big problem, Because hardware is fast growing.

C + + is the mainstream language at present, and I believe it will become a classic just like C.
to become a classic means that people who learn it can get a good salary, but it is only good for themselves.
in the future network world, go will have a big chance to get hot, I think it has a bright future.

the developers of go, including the founders of UNIX and C language, are the first generation of hackers, and I believe they will do a good job.

now the go stack + blockchain market is out of an unprecedented gale, and the situation is gratifying.

6. The mps() function performs the same serialization as the mp() function. Instead of accepting stream objects and saving serialized data to disk files, this function simply returns serialized data
the loads() function performs the same deserialization as the load() function. Instead of accepting a stream object and reading the serialized data from a file, it accepts the str object containing the serialized data and returns the object directly.

7. 1. Tianjin library is open to the public and can read freely, but at the same time, it needs to abide by the rules of Tianjin library. The entry notes of Tianjin library are as follows:

entry notes

& 9830; The museum is open to the public< br />
♦ Please pay attention to the appearance. Do not wear vest, slippers or spiked shoes< br />
♦ Please store your bags and other items in the bag storage cabinet before entering the borrowing area< br />
♦ Please take the books and periodicals out of the library after going through the lending proceres. Take the books and periodicals away without authorization and handle them according to the relevant regulations< br />
♦ Please keep quiet in the library area. Do not make noise or use audio communication tools in the reading area< br />
♦ Please take good care of the documents and all public property in the library, and compensate for the damage according to the regulations< br />
♦ Smoking and open fire are strictly prohibited in the library area. Do not bring inflammables and explosives into the library< br />
♦ Please keep the library clean, do not eat in the reading area, do not spit, litter, peel and other debris< br />
♦ Please consciously abide by the rules and regulations of the library and cooperate with the staff to manage according to the regulations< If you need to borrow books, you need to apply for the reader card of Tianjin library. The proceres are as follows:
1. General rules for applying for the card

1. Readers over 14 years old can apply for the reader card of Tianjin Library for the first time by holding their second generation ID card or other valid identity documents (social security card, driver's license, military card, Hong Kong and Macao pass, Taiwan compatriots' home return card, etc.) Foreign passport), fill in personal information and pay the corresponding deposit can be free of charge

2. For children under 14 years old to apply for Tianjin library reader card for the first time, their parents should hold the children's household register, fill in their personal information and pay the corresponding deposit for free

3. handles the ID number admission system for the reader's certificate of the library, that is, ID number can only be applied for a reader's certificate (other valid documents are also the same). The reader's card is valid for one year. After the expiration, the reader only needs to register with the card for free and can continue to use it (if someone else is entrusted to handle it, the agent should handle it with his ID card and the original ID card of the client)< According to the amount of deposit or the type of readers, the reader card has the following three service functions for readers to choose to open, and the three functions are not allowed to run at the same time

1. Chinese and foreign language literature lending function: readers can borrow one foreign language book in the cultural center by paying a deposit of 500 yuan; Five volumes of Chinese books can be borrowed from the three districts of the library and the district and county public libraries that have opened the loan and return service; Five Chinese periodicals can be borrowed from the cultural center and Fukang road; Read the collection of Chinese and foreign literature< 2. Chinese literature lending function: readers can borrow 5 volumes of Chinese books in the three districts of the library and the district and county public libraries that have opened the loan service by paying a deposit of 100 yuan; Five Chinese periodicals can be borrowed from the cultural center and Fukang road; Read the collection of Chinese literature

3. Children's literature lending function: readers can borrow 2 Chinese children's books in the cultural center by paying a deposit of 50 yuan; One children's journal; Read children's literature< (1) Chinese literature lending function: readers over 14 years old with their second generation ID card can apply for the new card on the self-service card machine, If you hold other valid certificates, you need to fill in the application form at the manual application desk< (2) the function of Chinese and foreign language literature lending: readers over 14 years old should hold their second generation ID card or other valid documents and fill in the application form at the manual registration desk

(3) children's literature lending function: children under the age of 14 who apply for Tianjin library reader card for the first time must be accompanied by their parents, carry their children's household register, fill in personal information and pay the corresponding deposit for free Special note: this card can only be used in children's literature lending room< Other kinds of certificates that have expired in our library in the past: readers holding such certificates must cancel the certificate at the manual registration desk (no overe fees, book records, deposit refunds, etc.) and apply for the new certificate according to the new certificate application method< 4. Report loss, supplement and refund of deposit

1. Report loss: when a reader accidentally loses his / her reader card, he / she should immediately report loss with his / her valid certificate. During the period of report loss, the service function of the reader card (except the book return function) is temporarily closed

2. Certificate replacement: one week after the loss of the certificate is reported, the reader will apply for a new certificate with his valid certificate. If the reader's card cannot be used normally e to personal damage, the reader shall apply for a new card with his own valid certificate

3. Refund of deposit: the reader holds his ID card and reader card, and the system confirms that there is no record of overe fees and books, fills in the refund application form, and the issuing office returns the deposit to the reader, and turns off the reader card borrowing function; If the agent is entrusted, the agent shall hold his ID card and the original ID card of the client. If the reader card is lost, the reader should return the deposit one week after reporting the loss. Please keep the reader card properly after returning the deposit. If you pay the deposit again, you can resume the borrowing function< The initial password of the reader card is the last seven digits of the card number or the full card number (letter + number). Please change your password by yourself. If you forget your password, please reset it at the certification office

2. The applicant of the reader's card shall be liable for the loss of the library's literature resources e to the loss of the reader's card or the password problem

3. Readers should check the reader card and cash in person ring the process of processing the reader card

4. The library's books and periodicals are loaned out for 30 days and can be renewed once ring the period. If the borrowed Chinese books and periodicals are overe, the overe service fee will be charged at the rate of 0.20 yuan / day / volume; If the books in foreign languages are overe, the overe service fee will be charged at the rate of 0.50 yuan / day / book

3. Address and bus information of Tianjin Library:

1) bus guide of Tianjin Library (cultural center area)

Tianjin Library (cultural center area) is located at 58 Pingjiang Road, Hexi District, Tianjin
readers of the city can take the following bus lines to get off at the cultural center library station (Wenyue Beili station):

K47 Road: Xianyang North Road Xianyang North Road
655 Road: Tianjin Haihe Ecation Park No.1 bus station Tianjin Culture Square
662 Road: Shuangma bus station west Jieyuan road
668 Road: East Gate of water park Liyuan small street District bus station
NO.686: Minhang Road Shuangma bus station
no.800: Lu road Benxi road
no.835: Jialing Nanli Tanggu University of science and technology
no.868: Fuli jinmenhu bus station xuzhuangzi bus station
no.912: cultural center bus station qingcuiyuan
foreign readers can take Metro Line 3 (from Tianjin station to South Station) Get off at Wujiayao station (exit A2), walk to decayli station, take air conditioning 47 (single floor) road, and get off at cultural center library station (Wenyue Beili station)
from the west station, you can take Metro Line 1 (to Shuanglin direction), get off at xiawafang station (exit C), walk to xiawafang station, take bus 668 (or 868), and get off at cultural center library station (Wenyue Beili station)

2) Tianjin Library (Fukang road library area) bus guide

Tianjin Library (Fukang road library area) is located at No. 15, Fukang Road, Nankai District, Tianjin
readers of the city can take the following bus lines to get off at Tianjin library station:
47 No.48: Xianyang North Road Xianyang North Road (Central Ring Road)
No.95: wangdingdi North Liulin
NO.175: Yangliuqing xiawafang
No.698: yashi bus station - Lushui renrenrenrenle
No.705 (West Road): xiguanxi Shuanggang xinjiayuan bus station
no.707: haiguangsi bus station - zhangjiawojiataili
831 Road: Central Park Haitai north bus station
no.845: Liuwei road Liujing road Houtai bus station
no.862: Sixth Avenue Haitai south bus station
no.866: taiyangcheng bus station Chengjiang road bus station
no.902: dajiangli wangdingdi bus station
foreign readers can take Metro Line 3 from Tianjin station (heading for South Station) From Tianjin South Station, you can take Metro Line 3 (heading for Xiaodian); From Tianjin west station, you can take Metro Line 1 (for Shuanglin direction) to Yingkou station and transfer to Metro Line 3 (for South Station direction). Get off at zhoudeng Memorial station (exit b) and walk 1.1km northward to


3) Tianjin Library (Haihe park area) bus guide

Tianjin Library (Haihe park area) is located at No.1, Xinhui Road, Haihe Ecation Park, Jinnan District, Tianjin
local readers can get off at Haihe Ecation Park Management Center Station by taking the following bus routes:
no.655: Tianjin Culture Square - Tianjin Haihe Ecation Park No.1 bus station
No.705 (East Road): TIBEI Station - Haihe Ecation Park No.2 bus station
from Tianjin station, readers can take Metro Line 3 (heading for South Station), Get off at Yingkou station, transfer to Metro Line 1 (to Shuanglin direction), get off at Fuxingmen station (exit b), walk to Fuxingmen station, take bus 655, and get off at Haihe Ecation Park Management Center Station
from the west station, you can take Metro Line 1 (to Shuanglin), get off at Fuxingmen station (exit b), walk to Fuxingmen station, take bus 655, and get off at Haihe Ecation Park Management Center Station.

8. Eth is a kind of digital token of Ethereum. Developers need to pay eth to support the application. Ether currency, like other digital currencies, can be traded. Generally speaking, Ethereum is an open source digital currency and blockchain, which provides developers with a platform to build on the blockchain

9. It is suggested that you buy an analysis book with examples and take a look at the above answer format, which should be helpful.
when answering questions, you should draw a stress analysis diagram and mark the direction of the force.
1, Secondly, it is clear which direction the object is in, who is exerting the force on it, and how much the force is.
3. According to Newton's law of mechanics and the conditions in the problem, the equation is listed, and the final result is obtained.
the knowledge points commonly used are: integral method and isolation method, the composition and decomposition of force, The following is a mechanical problem I have answered, hoping to give you some inspiration.
1. On the horizontal plane, there are rectangular blocks a and B in contact with each other, m (a) = 6kg, m (b) = 4kg, a horizontal right force of 5N acts on a, making them accelerate together, then the force between AB is:
analysis: let the dynamic friction coefficient be u, and the friction coefficient be 0, If the acceleration is a
and ab is regarded as a whole, and the force analysis is
then AB is subjected to the horizontal left friction F1 = u · (MA + MB) = 10u, and the horizontal right thrust f = 5N
then the acceleration a = (f-f1) ÷( mA+mB)=(5-10u) ÷ 10
according to the force analysis of B, it is known that B is pushed horizontally to the right by a, and the friction force to the left is F2 = u · MB = 4U
then the acceleration a = (f-f2) ÷ mB= (F-4u ) ÷ 4
connect the two formulas to get (5-10u) ÷ 10 = (F-4u ) ÷ 4
then f = 2n