C ＃ Foundation

C# Basics

C# Language is a kind of language developed by Microsoft object-oriented Programming language . It is characterized by encapsulation 、 Inherit 、 polymorphic , And added events and delegates , Enhance the flexibility of programming .

characteristic ：1、 Simple , Security .

2、 object-oriented

3、 Cross-platform support

4、 Can develop many types of programs

namespace Namespace name . Used to resolve naming conflicts .

When there are more than two named classes or methods with the same name , Use namespaces to distinguish which class or method we call .

C# The basic content of the program is contained in a namespace

F5 It is a shortcut key for debugging and running

Alt+F5 Direct operation

F11  Sentence by sentence . Each statement should be debugged and executed . When the function is executed , Enter the function to execute

F10  Process by process . Only perform each process . When the function is executed , Execute functions directly , Don't go inside the function .

shift+F11 Jump out of , Jump out of the function we are currently executing , Go back to the next level

C# Basic data type

Data types are mainly used to indicate the types of stored values of variables and constants .

C# The basic data types are Value type and Reference type .

Value type ： plastic 、 floating-point 、 Character 、 Boolean type 、 enum .

Reference type ： The class interface 、 Array 、 entrust 、 character string .

In basic data types , except string The others are value types .

The value type is passed Transfer value .

The reference type is passed The reference . Method

The storage unit of computer memory

bit position Values can represent 0 1（ The smallest unit of computing memory ） Binary system

B  Byte byte 1Byte=8bit

KB  1KB = 1024B

MB  1 MB =1024KB

GB  1GB = 1024MB

Basic data type — plastic

byte Unsigned byte type  1 Bytes 0~255 A signed sbyte -127~126

short Signed short shaping 2 Bytes Unsigned ：ushort

int There's symbolic plastic 4 Bytes      Unsigned ：uint

long Signed long plastic 8 Bytes Unsigned ：ulong

notes ： A byte can only represent English letters and some symbols

floating-point

float Single precision floating point 4 Bytes

example ：float num = 25.6f;

double Double precision floating point 8 Bytes

example ：double dNum = 25.6;

decimal Higher precision floating point 16 Bytes

example ：decimal decimalNum = 25.6M;

notes ：C# Small and medium numbers think that double type

Character char  2 Bytes

Only one character can be stored , Need to be enclosed in single quotes

example ：char c = ' I ';

String type

use string Deposit , It needs to be enclosed in double quotes

example ：string str = " I'm a string ";

Boolean type bool

value ：true and false

example ：bool isOK=false;

notes

effect ： Used to illustrate the meaning of the current code , Get rid of the code you don't need at the moment

The first one is Single-line comments //

example ：//Write Output only without line breaks

     Console.Write(" character string ");

The second kind Multiline comment /* Represents the beginning of a comment  */ Represents the end of the comment

example ：/*      int num = 5;

            int result = 0;

            */

The third kind of Documentation Comments Generally used for the description of classes and methods

example ：  /// <summary>

        /// This is a startup method ,Main Method

        /// </summary>

        /// <param name="args"></param>

        static void Main(string[] args) { }

       

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