What are the basics in C #

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C # fundamentals-data types

Float (single precision is 7 digits)

Double (double precision is 15 to 16 digits)

Decimal (decimal type has a smaller value than double but it is more accurate)

Decimal d_value = 1.0m / / subscript m is represented as a decimal type. If m is omitted, it is treated as double. Char c_value ='\ X0032' / / hexadecimal escape character char c_value ='\ u0032' / / Unicode representation char c_value ='A'; / / single quotation mark string s_value = "long" / / A double quotation mark string [] s = new string [6] / / character array {..} Click Show CodeShow Code [+] class Test {static void Main () {int [] A1 = new int [] {1,2,3}; / / one-dimensional int [,] a2 = new int [,] {{1,2,3}, {4,5,6}; / / two-dimensional int [,] a3 = new int [10,20,30] / / 3D int [] [] j2 = new int [3] []; / variable length j2 [0] = new int [] {1,2,3}; j2 [1] = new int [] {1,2,3,4,5,6}; j2 [2] = new int [] {1,2,3,4,5,6,7,8,9};}

Structure is a value type, not a reference type, so inheritance is not supported! The structure is stored in the stack or inline. The meticulous structure can improve the storage performance. For example, defining a structure that has the same information as a class can greatly reduce storage space

Struct Point {public int x, y; public Point (int x, int y) {this.x = x; this.y = y;}}

Enumerate

1. You can only take the value of one element in the enumeration at a certain time

two。 Each element type is int and the value of * elements is 0 and the elements that follow it are incremented by 1.

Enum WeekDay {Sunday,Monday,Tuesday} WeekDay day; day = Tuseday

Representative

1. The difference between the function pointer prototype and the pointer in C # means that it is type safe in C #.

two。 Declaration cannot have a return value or a parameter with an output type

Delegate int MyDelegate (); / / declares a representative that points to the prototype of a function of type int

Packing and unpacking

1. You can treat a value type as a reference type

two。 Boxing refers to the implicit or explicit conversion of a value type to an object type

3. Unboxing is an explicit conversion of object types to value types

Basic knowledge of C #-constants and static variables

The constant itself is in the form of a value and no space is allocated in memory; static variables are variables that need to be allocated in the form of memory.

Public static string s_value = "this is a" + s_dog; / / assume that s_dog is another variable initialization value can be changed according to different s_dog public const double X = 1.0, Y = 2.0 / value can not be changed

Basic knowledge of C #-Type conversion

(type) variable

Convert.toXXX (variable)

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