Black Horse programmer -01-c Language overview

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First, computer and software knowledge 1. Principles of computer operation

1) Hardware basic components: Hard disk, memory, CPU

2. Computers can only recognize 0 and 1

1) instructions consisting of 0 and 1

2) data consisting of 0 and 1

3. Connection of computer and software

1) Basic concept of the software: a set of instructions

2) Software Installation and operation process

U mounted on hard drive

U Run in memory

3) Why develop software: Write instructions to control your computer

4. Computer language

1) A language that deals with computers

2) Easy to write a series of instructions

II. History of computer language

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.

Iii. Introduction to C language 1. The reason for learning C language first

1) OC based on C

2) OC and C's thought and grammar are different in many places, and OC can be mixed with C

3) c is the classic of all programming languages, many high-level languages are derived from C language, such as C + +, C #, OBJECTIVE-C, etc.

2. Brief History

1) The C language was invented in 1972 and was first used to rewrite the Uinx operating system (Unix was written primarily in assembly language, which laid the foundation of the operating system)

2) with the success of Unix operating system, C language has been greatly promoted, has been used in large, medium and small, micro-host, is still the world's most popular, the most widely used high-level programming language One

3) C language is a process-oriented language, non-object-oriented language

3. Features

1) Rich operator

2) Rich data types

3) can operate the hardware directly

4) Efficient target code

5) Good portability

4. Main uses

1) write system software, graphics processing, single-chip microcomputer program, embedded system development

2) write the game plug-in

3) Writing Android programs

4) Writing iOS programs

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Black Horse programmer -01-c Language overview