(4) C # variables, constants, data types, data conversions

1. Variables

The amount of time that can be changed while the program is running

Define and initialize

3.14

2. Constants

The amount of time that a program cannot be changed while it is running, and it can be any basic data type .

such as Integer constants, floating-point constants, character constants, or string constants, as well as enumeration constants

Methods for defining constants

Add a keyword "const" before defining a variable

Const int a=;

3. Data type

There are three types of data in C #, value types, reference types, and pointer types.

Value type

Also known as the basic data type, each value type has a separate memory area to hold its own value, and calls it when it calls his value.

type	Description	Range	Default Value
bool	Boolean value	True or False	False
Byte	8-bit unsigned integer	0 to 255	0
Char	16-bit Unicode characters	U +0000 to u +ffff	' + '
Decimal	128-bit exact decimal value, 28-29 significant digits	( -7.9 x 1028 to 7.9 x 1028)/100 to 28	0.0M
Double	64-bit double-precision floating-point	(+/-) 5.0 x 10-324 to (+/-) 1.7 x 10308	0.0D
Float	32-bit single-precision floating-point	-3.4 x 1038 to + 3.4 x 1038	0.0F
Int	32-bit signed integer type	2,147,483,648 to 2,147,483,647	0
Long	64-bit signed integer type	923,372,036,854,775,808 to 9,223,372,036,854,775,807	0L
SByte	8-bit signed integer type	128 to 127	0
Short	16-bit signed integer type	32,768 to 32,767	0
UInt	32-bit unsigned integer type	0 to 4,294,967,295	0
ULong	64-bit unsigned integer type	0 to 18,446,744,073,709,551,615	0
UShort	16-bit unsigned integer type	0 to 65,535	0

Reference type

(4) C # variables, constants, data types, data conversions