In-depth C # data types,

In-depth C # data types,

C # Common Data Types

Common Data Types java C # example

Int age

Float results

Double circumference Rate

String string String home address

Whether boolean bool is a minority

Enum color

Value Type

The value type is derived from the System. ValueType family. Each value type object has an independent memory region used to save its own value. The memory region of the value type data is called a Stack)

Value types mainly include basic data types (such as int, float, and double)

Case:

Int heightzhang= 170;

Int heightli = heigtzhang;

Console. writeLine ("Zhang Hao's score last year:" + heightzhang + "Li Ming's score:" + heighli );

Heightli= 180;

Console. writeLine ("Zhang Hao's score last year:" + heightzhang + "Li Ming's score:" + heighli );

Reference Type

The reference type is derived from the System. Object family. in C #, the reference types mainly include arrays, classes, and interfaces.

Case:

Int [] infozhang = new int [] {179,60 };

Int [] infoli = infozhang;

Console. write ("last year, Zhang Hao's height was:" + infozhang [0] + "Weight:" + infozhang [1] + "Li Ming's height is: "+ infoli [0] +" Weight: "+ infoli [1]);

Infoli [0] = 180;

Infoli [1] = 70;

Console. write ("last year, Zhang Hao's height was:" + infozhang [0] + "Weight:" + infozhang [1] + "Li Ming's height is: "+ infoli [0] +" Weight: "+ infoli [1]);

Subitem type and reference type

Data Type Classification

Category Description

Value Type basic data type Integer: int

Long Integer: long

Float

Double Type: double

Character Type: char

Boolean: bool

Enumeration type enumeration: enum

Structure Type Structure: struct

Reference Type Base Class: System. Object

String: string

Custom class: class

Interface: interface

Array: int [], string []

Structure

Public int id;

Public int age;

Public int Id {

Get {return id ;}

Set {id = value ;}

}

Public int Age {

Get {return age ;}

Set {age = value ;}

}

Structure Definition

Access modifier struct structure name {
// Result body
}

The structure definition has the following features:

1. The structure can contain fields or methods.

2. During definition, fields in the structure cannot be assigned a value.

Public struct Student {
Public int id;

Public int age;
}

Structure usage

The structure is similar to the class. When using the structure, pay attention to the following aspects:

1. You can directly define the structure object without using new'

2. After declaring the object of the structure, the initial value must be assigned to the structure member.

Public struct Student {

Public int id;

Public int age;

Public void Show (){
Console. writeLine ("ID: {0} \ n age: {1}", id, age );
}
}

Static void Main (string [] args ){
Student stu;

Stu. id = 1001;

Stu. age = 20;

Stu. show ();
}

Structure usage experience

The structure is a value type, and the declared Structure Variable stores a new copy of the structure, that is, the system needs to open up a new storage space. Therefore, the more the structure is used, the more space it consumes.

Packing and unpacking

We can say that data types can be divided into value types and reference types by storage method, and they can still be converted to each other. The process of converting a value type to a reference type is called packing, and vice versa.

Static void Main (string [] args ){
Int I = 123;

Object o = I;

I = 456;

Console. writeLine ("value type value: {0}", I );

Console. writeLine ("reference type value: {0}", o );

}

Unpack

Int I = 123;

Object o = I;

Int j = (int) o;

Passing different types of parameters

1. Use value transfer. Changes to parameter values in the method cannot be retained after the call.

2. Therefore, the ref method is passed and changes to the parameter value can be retained.

Value mode parameter transfer

When a value type parameter is passed, the parameter can be of the reference type or value type.

Use the reference type as a parameter

Class Voter {
Public void Vote (SE se ){
Se. Popularity ++;
}
}

SE zhang = new SE ();

Zhang. Age = 25;

Zhang. Name = "zhang Jing ";

Zhang. Gender = Gender. female;

Zhang. Popularity = 10;

MessageBox. Show (zhang. SayHi ());

Voter voter = new Voter ();

Voter. Vote (zhang );

MessageBox. Show (zhang. SayHi ());

Parameter transfer in Reference Mode

1. Use the reference type as the parameter

Private void Vote (ref SE se ){
Se. popularity ++;
}

2. Use the value type as a parameter

Private void Vote (ref StructSE se ){

Se. popularity ++;

There is no difference between the two parameters passed in the ref method, and the changes in the method will be saved.

}

 

 

Unpack