The C language of "Wan FA gui"

First, let's take a look at the version of this issue:

　　　　

1) In 1983, the U.S. National Bureau of Standards (American Nation Standards Institute, abbreviated as ANSI) set up a committee to begin work on the C language standard

2) 1989 C language standard is approved, this version of the C language standard is commonly referred to as ANSI C

3) In 1999, ISO also revised the C language standard, on the basis of basic retention of the original C language features, in response to the needs of the need to add some features, named C99

4) December 8, 2011, ISO formally publishes the new International standard of C language draft: C11

Let's show you a picture:

　　

It reflects the ranking of programming language activity. One or two of them are C and the Java chaos Occupy, I believe we also see that 1-5 of the language, of which 3 are with "C". It can be understood that C language is the basis of all programming languages. As a child to school, math, teachers teach you Arabic numerals. Chinese, the teacher teaches you to read and write letters and pronounce. Moreover, most of the programming language is derived from the C language, it can be said that C language is the cornerstone of it!

Let's summarize the development of the programming language in the process of computer development:

1. Machine language

1) Introduction: All code inside only 0 and 1, each instruction is called "Machine instruction"

2) Advantages

U code can be directly recognized by the computer, directly to the hardware, program execution efficiency is very high

u can directly access and control the various hardware devices of the computer, such as disk, memory, CPU, I/O port, etc.

3) Disadvantages

The U program is full of 0 and 1 instruction codes with poor readability and error-prone

U is very dependent on hardware, so the machine language of different models of computer is not the same. That is to say, if 2 different models of machines want to achieve the same function, you need to write 2 sets of completely different code

You have to memorize all the instructions and instructions of the computer you are using, and the instructions are more difficult to remember.

4) Use the occasion

In summary, machine language is difficult to master and promote, now in addition to computer manufacturers of professionals, the vast majority of programmers have no longer to learn machine language

2. Assembly language

1) Introduction: Replace machine instructions with English words and other symbols

2) Advantages

U like machine language, you can directly access, control the computer's various hardware devices

You use less memory and perform faster

3) Disadvantages

U different machines have different assembly language syntax and compilers, code lacks portability, that is, a program can only be run on one machine and not run on another machine

The U symbol is very many, difficult to remember, even if the completion of simple functions also require a lot of assembly language code, it is easy to produce bugs, difficult to debug

U must know the hardware very well, the development efficiency is very low, the cycle is long and monotonous

4) Use the occasion

U operating system kernel, driver, microcontroller program

Encryption, decryption and decoding of U software

Manufacture and prevention of U virus

debugging and Analysis of U program

3. Advanced language

1) Introduction: Close to natural language

2) Advantages

U simple, easy to use, easy to understand, syntax and structure similar to general English

U away from the direct operation of the hardware, so that the average person after learning can be programmed, without being too familiar with the hardware knowledge

U a program can also be run on different machines, with portability

3) Disadvantages

U program can not be directly recognized by the computer, it needs to be translated into binary instructions by the compiler to run to the computer

4) Kinds: C language, C + +, C #, Java, objective-c, etc.

4. Comparison of three languages

To write a program that calculates the last one, using machine language, assembly language, C language (high-level language), respectively

1) Machine language: It is a heavenly book!!!

10111000 00000001

00000000 00000101

00000001 00000000

2) Assembly language: Readability a little better, but trouble

MOV ax,1

ADD ax,1

3) C language: Streamlined, easy to understand

Up

According to the above analysis, it is not difficult to see. People have been developing programming languages into a language that is more familiar and quick to master.

The C language of "Wan FA gui"