Hello world! (Hello, world!)

Hello world! (Hello, world!)

"Hello, World", this is the most basic and simplest program in every computer programming language, and the first program we started writing to determine the compiler, program development environment, and whether the running environment is installed properly.

"Hello world!" program, as the first program written, has now become a precious tradition!

"Hello World"-"Hello, the earth", for us to open the door of a new world, in the computer world, has countless wonderful and legendary, there are countless regrets and regret. What kind of story can we run in this world again? Let's get Started:

Infatuation with Hello World

Programming that the school won't teach you anything

The peak of the tide

Programming, we need a little basic computer system

Computer is a very large system, the main areas can include: computer system structure, program design, software engineering, artificial intelligence, network, database and other auxiliary technology, algorithm theory.

Computer = hardware + software

Computer system can be said to be hardware and software two parts. Hardware includes CPU, memory, hard disk, input, and other external devices. These hardware devices provide a physical basis for the operation of the software, the software must be based on the hardware to run, the role of computer hardware is to store and run the software.

Computer software refers to the procedures and data in a computer system. The various powerful functions that the computer system presents to the user are implemented by the software.

software : A computer system in which a series of computers can recognize and execute instructions that can be run by loading into the computer's memory. For example, a "calculator" software, starting after the first run in memory, by converting the user's input information into a number of subtraction operations, and converted to the computer hardware can understand the instructions, and then send instructions to the CPU to operate, the end result output to the user.

operating system is also the operation of software computer system needs a lot of software to support, broadly divided into system software and application software, System software refers to the various types of operating systems we usually use, unix,linux,windows7 and so on. Application software value operating system on the various programs, such as: Vim,office 2003,qq. To be able to develop these software, we need a computer programming language, which is a way to communicate with computers.

Computer hardware

So-called: "Man-machine Interaction"

Interactive? Is that we can make the software through contact with the computer like Avatar, so that we can generate induction? When ~ ~ Then, no!

Human-Computer Interaction is through the human-computer interface (that is, the interface of the software, with the mouse to launch, the missile will launch the kind of graphical interface) and the system to communicate and operate. Small as the radio play button, large to the Shenzhou number on the instrument panel.

Here we borrow this word, we will write the program (software), and run on the computer, if we write the code is not a problem (with the mouse click to launch a missile, this is to fight the enemy, the result of the missile in the enemy positions in a circle and back to blow themselves, this is called Program logic error), The computer will feed back a result that we want.

The programming language serves as an important part of our communication between humans and computers.

Types of programming languages

Machine Instructions : computer work is based on binary (0 and 1 encoding), only can recognize the instructions consisting of 0 and 1, the composition of the language is called machine language. Because the machine language is very difficult to write , so later in the assembly language, through some similar add,sub symbols to write programs, and then use the assembler to convert to machine language. Assembly language still depends on the hardware state of the computer, it is difficult to run on different machines, so it belongs to the low-level language.

the advent of high -level languages: low-level language writing software is really too abusive , so there is no reliance on specific computer hardware high-level language. Programs written in high-level languages (source programs) can be translated into machine languages (target programs) and run on different models of computers. A high-level language is compiled into multiple machine languages. At present, there are thousands of kinds of high-level languages in the world, and the development is divided into three stages: unstructured language, structured language and object-oriented language. C language belongs to the structured language, and the program flow consists of sequential structure, branch structure and cyclic structure. C++,c#,java, which belongs to object-oriented language, is based on object as the basic program structure unit.

Program Run Process

Programmers design the framework of the program, and then write the implementation in a high-level language, resulting in a number of source program files. Some languages need to be converted to a binary machine language using a compiler, which can then be executed on the computer, which is called a compiled type. Some languages do not require a compiler and are directly interpreted by the interpreter to run, such as an interpreted language, or a scripting language, such as Python,ruby. The interpreted language needs to be interpreted each time it executes, while the compiled type only needs to be compiled once.

Programming languages

Programming, there is a way of OH

Computer technology, especially programming language is a practical science, learning process needs a lot of hands-on practice, there is no legendary shortcut, only constant practice , to do the project can be harvested. The best way is to keep going crazy coding.

Roughly divided into four steps: Theoretical basis, code reading, hands-on practice, open source projects. Well, in fact, you need to have a computer that can surf the internet and log into the experimental building.

Theoretical basis

Through some books or experimental building tutorials in the document part of the system learning, for programming language needs to learn some syntax and keyword usage, for the system management knowledge needs to learn software deployment and configuration, command use and so on. This knowledge does not require rote memorization, only need to understand, in the follow-up process to use the natural impression will be much deeper.

Code Reading

Read the code for some small projects developed by the programming language and analyze them. Can be found on GitHub, the experimental building project code is placed on GitHub, you can directly find. When it comes to code analysis, look back at the previously learned theories, which grammars and keywords are applied, and why.

Hands-on practice

With a certain code reading can start to write some small programs, these programs can directly find the existing code to combine, such as the experimental building in the project class, you can directly follow the code sample to copy. The aim is not to be novelty, but to increase the proficiency of the language. When you actually write a program that you can run according to the documentation of the project lesson, the sense of accomplishment is enhanced and you are more confident and interested.

Open Source Projects

When you practice several projects, you can participate or create some open source projects yourself. This stage is a big challenge, it will be a bit painful, because you have to use the language you learn to solve real problems, innovation, need to think about digesting the previous theoretical basis and project experience, and gradually learn to flexibly use programming language to achieve their own logic and purpose. In the development of open source projects can seek the experimental Building forum and technical community, Google search, StackOverflow help.

Career path

The development of the Internet has made the real technical personnel never lack of good salary and position. The treatment in the IT field is quite impressive.

Due to the technical breakdown, it engineers will also be divided into a number of positions according to the technical field of choice, the current mainstream classification methods can be divided into: Research and development, testing, operation, dba several major categories , research and development engineers can be divided into Java, C + +, PHP, Hadoop, Web front-end, Android, iOS and other segments of the position, the same test can be divided into: Test Engineers, test development, etc. , we can go to the major recruitment site to find more and more detailed positions.

Although now is an open era, companies are in eclectic recruit talent, but really can do the work of the engineer is the company's favorite, flashy will always be eliminated. Although each position seems to be different career development path, it or the process of thinking are interlinked, the position between each other often occurs, has a wealth of practical experience is always an important factor in the success of the job.

We all like it, like computers, just want to engage in this industry, not because of the benefits of this factor to choose. In the film "In the Boat", the landlord saw the protagonist to write a dictionary throughout the night to look at the material, said: "When young can find their favorite and do a lifetime of things is how happy how admirable ah."

Hello World, just a start ...

Hello world! (Hello, world!)