2020/3/21 simple learning

2020 March 21

Computer systems

• Input device: a mouse, a keyboard, a microphone, a scanner

• An output device: a display, speakers, printer,

• Central processing unit (cpu):
  • Operator: responsible for data operations
  • Controller: instructions to help get cpu calculator
  • Register: data storing operation for cpu
  • Prefetcher: fetching instructions from program memory
  • MMU: virtual memory mapping
• The memory (RAM):
  • ROM: read-only memory (read only memory)
  • RAM: read and write (random access memory)
  • Memory by "electrical" data storage, data can not be persistent. A little: quick read.
• External memory (hard disk):
  • Using hard "magnetic signal" stored data may be persistent storage. Disadvantages: slow read and write data.

Hardware system

Host part

• cpu

• Internal memory

Peripheral part

• Input device: read.
• Output Device: write.
• External memory: persistent storage

Software system

system software

• operating system

  • Excellent commercial companies, organized the compilation of the underlying open source program for managing hardware
  • The concept: the operating system is a computer program managing computer hardware and software resources. Nature: Program
  • down:
    • Drivers, hardware management
  • Improvement:
    • GUI: ordinary users
    • Terminal Interface: ordinary users, developers can be used (cmd)
    • System call: the operating system available to developers to use the function
  • Common operating systems:
    • Windows: Microsoft
    • macOS: Apple
    • Linux
    • Unix

• Language processing system

• System Services

• Database Management Systems

application

Select the application software on demand

• File Handling
• Graphics processing
• Forms processing
• Real-time control

Programming languages ​​and compilers

• Programming languages: control computer hardware work

Common C / C ++ compiler:

• Borland C ++ sapphire blue company
• Intel Intel C ++ Compiler
• Microsoft VC ++
• g ++ compiler (gcc compiler suite), Linux default used by the compiler, support for standard best

The advantages and disadvantages of C language

advantage:

• Lower learning costs

• Run faster

• Powerful

Disadvantages:

• Code to achieve long cycle

• Transplantable gender differences

• Experience requirements for high

• Multi-platform library dependencies

C language applications

• server.
• operating system.
• The upper application. MFC, QT

• Embedded.

• Artificial intelligence, hardware drivers.

• Middleware.

• Network attack and defense, data security.

• University compulsory

• Famous enterprises, foreign invested enterprises

C-32 Image

• auto、break、case、char、const、continue、default、do
• double、else、enum、extern、float、for、goto、if、int
• long、register、return、short、signed、sizeof、static、struct
• switch、typedef、unsigned、union、void、volatile、while

C-nine kinds of control statements

• if····else···
• for（；；）····
• while（）·····
• do···while（）·····
• continue
• break
• switch
• goto
• return`

34 kinds of C language operators

• Arithmetic operators: + - * /% + -

• Relational operators: <<= ==> => =!

• Logical Operators:! && ||
• Bitwise operators: << >> | ~ ^ &

• Assignment operator: = its extension

• Conditional operator:? :

• Comma operator:,

• Pointer operators: * &

• Logarithmically bytes: sizeof

• :( cast type)

• Component calculating: ->

• Subscript operator: []

• Other :()

Common IDE

• IDE: set editor, compiler, debugger, and a collection of tools
• Windows：
  • VS2013、VS2015、VS2017、VS2019
  • Clion: Cross-platform IDE
  • QT Creator: cross-platform IDE
  • Eclipse
• MacOS：
  • Xcode
  • Clion: Cross-platform IDE
  • QT Creator: cross-platform IDE
  • Eclipse。
• Linux：
  • vi / vim-- text editor
  • Clion: Cross-platform IDE
  • QT Creator: cross-platform IDE
  • Eclipse。

System Functions

• Specifies the Windows command execution system: the role of
• command:

#include <stdio.h>
#include <stdlib.h>
int main()
{
    printf("hello world");
    system("pause");
}