C, C ++, Java, javascript, database language
I would like a representative from five languages above, to organize my understanding of the code:
When at first, no programming language, the computer was first invented, computers only know binary, that is, 0 and 1, but can only perform mathematical calculations, because it is a different way of expressing decimal numbers in binary in nature, although only can perform mathematical calculations, but we can write an equation solver let the computer, and the computer can perform complex equation to solve, we can even write branch operation, so after the invention of the computer quickly explore three aspects of their fists in the government research universe, because these three areas require complex data and statistical computing. Later, IBM introduced the PC business, namely mainframe flagship bank companies and schools, because of its relatively low price, while mainframe programming and support customer operations on it, but IBM can not make everyone use binary programming, assembly language appear so , the assembly language is once again above the binary package, through friendly semantics of command, so that customers can easily write a program, while the assembly language into binary computer will be performed, and then later, a new problem arises, because IBM each is individually customized mainframe system, every time you need to replace the computer, means that the original program needs to write new again, very customer complaints, so IBM introduced IBM360, this is a new field, IBM first proposed operating system, computer hardware and software that is separated, each time the customer needs to replace the computer, and then do not need to rewrite the program, because each mainframe operating system above all a system, but the system is to use the IBM assembly language written in assembly language is very effective at writing small programs, But in the preparation of a very large project, assembly language problem arises because large system inside, such as the type of memory operation if switch data file read data manipulation, etc. are very common operation, and assembly language without these the concept, if developers need to achieve in order to put to use if, then the new language appeared, this is C, C is in assembly language to the next level, he encapsulates some of the basic concepts needed for large-scale projects, so that developers can focus on writing business, programs written in C language can also use assembly language, c language will only faster developed it, is frequently used in assembly language development process to package some of the concepts into the language, eventually developed using the c language program still will be compiled into assembly language, assembly language c language essentially be the underlying cpu command execution, so c language gradually became popular, the latter as more and more demand, more and more projects, organize your code is becoming a problem, because there is no concept c language package, all the code is finally together the developers in cooperative development process had to be careful handling code, because in C ++ appear, people development is the operating system, the amount of code required for operating system is very large, so C ++ appeared, he proposed object-oriented modular two important concepts, makes the problem more than to develop greatly eased, C ++ should underlying This is translated directly into assembly language or directly compiled into machine language, so compile C C ++ on top of the operating efficiency should be consistent, higher degree that they are essentially binary language package, people in the programming language from 1960 1980 to explore for 20 years, eventually refined the C ++, Actually in the process of continuous development has been part of some common ideological language to abstract a way out, if the compilation c c ++ to explore belongs to all mankind, the latter language is mainly based on commercial decisions and created language the birth of java because the sun's hope to achieve an operating system to run on all of the physical device, so that you can achieve things, sun's strategy is to write a java virtual machine, and then the java virtual machine running in the operating system, then use the java language to write a java virtual machine can run the system, and ultimately java virtual machine or the java bytecode into machine code execution, so although java achieve a cross-platform, but in terms of efficiency is not as good as c ++ c of, javascript browser level, if we think carefully about it, the browser is essentially achieve the sun's desire, the browser is essentially a virtual machine, while the javascript is essentially java, so we use js to write good programs after the final browser needs to js bytecode into machine code and then take the machine to perform, So js operating efficiency is also very slow, it was discovered that the operation is the database language data is very frequent and time-consuming, so we invented a database specifically for data processing, database software for data query and so do the extreme optimized at the cost you have to use its language to write, it is well understood, in fact, is what you use to take advantage of his rule and his optimization measures to achieve the purpose of optimizing the operation of the data, so the language is essentially divided into two one kind is run directly language on the computer, one is running language on software, java js database language is to run the language in the software, and c c + is run directly language on the computer, run the language in the software also is called an interpreted language, namely software need to constantly explain the program and then converted into the underlying binary commands, there is a transformation of the reading time there, which is why js very slow reason.
There are dozens of programming languages, but in fact can be summed up,
1: characteristics of the language itself
++ to java js from c c we find that there are always some of the concepts are the same, including data types, variables, constants, branch loops, functions, modular, object-oriented, although they realize the way is not the same, but the idea is basically the same just different manifestations of it
2: api platform where
The birth of each language has its significance before c ++, api is dealing more with the computer file including reading, multithreading, memory processing, network communication. However js appear here things change, castrated js file read and multithreading both areas, only joined in recent memory handling this piece of content, it appears ajax processing network read in 2003, the corresponding increase in the dom js bom and where the platform used to access the api, api and the essence of the platform where the platform is to read the information and use the platform to perform specific functions, if later mature vr, vr bound to a language, apart from including the previously mentioned language features, also including the use of api vr to perform specific functions.
3: Industry agreement
After the emergence of business language, the language more linked with the industry, erp software for business knowledge highly valued, it may not be the banking sector how high your skills, but you precipitating the industry, you can your the combination of technology and business has to solve specific problems, every industry will specify the common protocol, web industry built http1.0 http1.1 http2.0 over tcp, there will be some common agreement erp industry norms,
Code organization itself:
Language ability is just a carrier, we have to perform specific functions through according to the language and platform api, as the project is growing, organization and code maintenance is becoming a problem, object-oriented and mvc two ideas is the essence of decoupling, we need to decouple a complex project, while decoupling there are two common solutions: Object-oriented and problem-solving two mvc they were level, object-oriented software development process is complicated by different things abstract problem to achieve the sort of program logic, mvc is an idea and condensed in the process of developing specific interfaces, for parallel development and code reuse by the reduction achieved separately from the data item view complexity,