(C#) Implement verification code function code

Create a new page specifically used to create verification code pictures
Its background cs file code is as follows:
PageLoad

Copy the codeThe code is as follows:

private void Page_Load(object sender,  e) 
{ 
string checkCode = CreateRandomCode(4); 
Session["CheckCode"] = checkCode; 
CreateImage(checkCode); 
} 

Where CreateRandomCode is a custom function, and the parameters represent the number of verification code bits

Copy the codeThe code is as follows:

private string CreateRandomCode(int codeCount) 
{ 
string allChar = "0,1,2,3,4,5,6,7,8,9,A,B,C,D,E,F,G,H,I,J,K,L,M,N,O,P,Q,R,S,T,U,W,X,Y,Z"; 
string[] allCharArray = (','); 
string randomCode = ""; 
int temp = -1; Random rand = new Random(); 
for (int i = 0; i < codeCount; i++) 
{ 
if (temp != -1) 
{ 
rand = new Random(i * temp * ((int))); 
} 
int t = (35); 
if (temp == t) 
{ 
return CreateRandomCode(codeCount); 
} 
temp = t; 
randomCode += allCharArray[t]; 
} 
return randomCode; 
} 

CreateImage is also a custom function used to generate graphs.

Copy the codeThe code is as follows:

private void CreateImage(string checkCode) 
{ 
int iwidth = (int)( * 11.5); 
 image = new (iwidth, 20); 
Graphics g = (image); 
Font f = new ("Arial", 10, ); 
Brush b = new (); 
//(new (),0,0,, ); 
(); 
(checkCode, f, b, 3, 3); 
Pen blackPen = new Pen(, 0); 
Random rand = new Random(); 
for (int i=0;i<5;i++) 
{ 
int y = (); 
(blackPen,0,y,,y); 
} 
 ms = new (); 
(ms,); 
(); 
 = "image/Jpeg"; 
(()); 
(); 
(); 
} 
//(new (),0,0,, ); 
(); 

Both methods can change the background color of the generated image. The following for loop is used to generate some random horizontal lines
Just add a <asp:Image> control to the page where the verification code is needed, but point ImageUrl to the page where the verification code is generated.

Copy the codeThe code is as follows:

<asp:Image Runat="server" ID="ImageCheck" ImageUrl=""></asp:Image>