Method for generating guid in C #

How do I generate a guid in C? We hope you can answer the following questions.

1. a guid is a 128-bit integer (16 bytes). When using a unique identifier, you can use this integer between all computers and networks.

2. The GUID format is "XXXXXXXX-XXXX-xxxxxxxxxxxx", where each X is a hexadecimal number in the range of 0-9 or a-f. For example, 337c7f2b-7a34-4f50-9141-bab9e6478cc8 is a valid guid value.

3. No duplicate guid value is generated on any two computers in the world. GUID is used to assign a unique identifier to a network or system with multiple nodes and computers.

4. On Windows, GUID is widely used: Registry, class and interface identification, database, or even automatically generated machine name and directory name.

The following C # command line program describes the use process:

Using system;

Namespace displayguid {

Class guidexample {

Static void main (string [] ARGs ){

Generateguid ();

}

Static void generateguid (){

Console. writeline ("guid:" + system. guid. newguid (). tostring ());

}}}

The following is the output of this program: (although the guid between different systems is changed .)

Guid: 9245fe4a-d402-451c-b9ed-9c1a03167482

A guid can be used to operate a primary key in the background database. The following code uses a guid to store information in a background database, which contains the following columns:

Pk_guid-uniqueidentifier Data Type

Name-nvarchar Data Type

In this case, a simple windows form containing a text box appears. When the button is selected, the data in the text box is inserted into the database. You can use the program code to generate a guid and store it in other columns:

Using system;

Using system. drawing;

Using system. collections;

Using system. componentmodel;

Using system. Windows. forms;

Using system. Data;

Using Microsoft. applicationblocks. Data;

Namespace guiddbexamplecsharp {

Public class frmbuildertest: FORM {

Private Label lblname;

Private textbox txtname;

Private button btninsert;

Private container components = NULL;

Public frmbuildertest (){

Initializecomponent ();

}

Static void main (){

Application. Run (New frmbuildertest ());

}

Private string generateguid (){

Return System. guid. newguid (). tostring ();

}

Private void btninsert_click (Object sender, system. eventargs e ){

String cs = "Server = (local); initial catalog = northwind; Integrated

Security = sspi ";

Using (sqlconnection conn = new sqlconnection (CS )){

Try {

String sqlinsert = "insert into DBO. tblbuildertest (pk_guid, [name]) values ('"

+ System. guid. newguid (). tostring () + "','" + txtname. Text + "')";

Conn. open ();

Sqlhelper. executenonquery (Conn, commandtype. Text, sqlinsert );

} Catch (exception ex ){

System. Console. Write ("error:" + ex. Message );

}}}}}

Another guid program assigns a unique identifier to A. Net class or interface. That is, the guid is assigned to a class or interface as an attribute. You can use the standard attribute syntax to implement this process:

We can extend the first example to assign a guid. The system. runtime. interopservices space name must be referenced to use the guid attribute. The following C # code implements this process:

Using system;

Using system. runtime. interopservices;

Namespace displayguid {

[GUID ("9245fe4a-d402-451c-b9ed-9c1a04107482")]

Class guidexample {

Static void main (string [] ARGs ){

Generateguid ();

}

Static void generateguid (){

Console. writeline ("guid:" + system. guid. newguid (). tostring ());

}}}

Format description

 

N 32-bit:

XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX

For example, e92b8e30a6e541f6a6b9188230a23dd2

D 32-digit numbers separated by a hyphen:

XXXXXXXX-XXXX-xxxxxxxxxxxx

Such as: e92b8e30-a6e5-41f6-a6b9-188230a23dd2

B is a 32-bit number separated by a hyphen in braces:

{XXXXXXXX-XXXX-xxxxxxxxxxxx}

Example: {e92b8e30-a6e5-41f6-a6b9-188230a23dd2}

P contains a 32-bit number separated by a hyphen in parentheses:

(XXXXXXXX-XXXX-xxxxxxxxxxxx)

(E92b8e30-a6e5-41f6-a6b9-188230a23dd2)

Do you understand?