这个程序主要是先生成一个随机数，然后根据生成的随机数经过变换后作为XBM图片的内容，最后显示这个图片. 验证时中要获取输入的数字和Session("validatecode")比较，如果相等则通过验证（还要注意一下相比较的两数据的类型保持一致）。

　　如何显示生成的图片呢？ <img src="xbm.asp"></img>

　　关于XBM图的格式信息，看这里
　　

　　xbm.asp的代码如下
　　程序代码：
　　<!--#include file="numcode.asp"-->
　　<%
　　@#开启缓冲
　　Response.Buffer = True
　　With Response
　　 .Expires = -1
　　 .AddHeader "Pragma","no-cache"
　　 .AddHeader "cache-ctrol","no-cache"
　　End With

　　Dim num
　　Randomize
　　num = Int(7999 * Rnd + 2000)
　　Session("validateCode") = num

　　Dim Image
　　Dim Width, Height
　　Dim digtal
　　Dim Length
　　Dim sort
　　Dim hc
　　Length = 4
　　hc = chr(13) & chr(10)

　　Redim sort(Length)

　　digital = ""
　　For I = 1 To Length - Len(num)
　　 digital = digital & "0"
　　Next
　　For I = 1 To Len(num)
　　 digital = digital & Mid(num, I, 1)
　　Next
　　For I = 1 To Len(digital)
　　 sort(I) = Mid(digital, I, 1)
　　Next
　　Width = 8 * Len(digital)
　　Height = 10

　　Response.ContentType = "image/x-xbitmap"

　　Image = "#define counter_width " & Width & hc
　　Image = Image & "#define counter_height " & Height & hc
　　Image = Image & "static unsigned char counter_bits[] = {" & hc

　　For I = 1 To Height
　　 For J = 1 To Length
　　Image = Image & a(sort(J),I) & ","
　　 Next
　　Next

　　Image = Left(Image, Len(Image) - 1)
　　Image = Image & "};" & hc

　　Response.Write Image
　　%>

　　Numcode.asp的代码如下：
　　程序代码：
　　<%
　　Dim a(10,10)
　　a(0,1) = "0x3c" @#数字0
　　a(0,2) = "0x66"
　　a(0,3) = "0xc3"
　　a(0,4) = "0xc3"
　　a(0,5) = "0xc3"
　　a(0,6) = "0xc3"
　　a(0,7) = "0xc3"
　　a(0,8) = "0xc3"
　　a(0,9) = "0x66"
　　a(0,10)= "0x3c"
　　a(1,1) = "0x18" @#数字1
　　a(1,2) = "0x1c"
　　a(1,3) = "0x18"
　　a(1,4) = "0x18"
　　a(1,5) = "0x18"
　　a(1,6) = "0x18"
　　a(1,7) = "0x18"
　　a(1,8) = "0x18"
　　a(1,9) = "0x18"
　　a(0,10)= "0x7e"
　　a(2,1) = "0x3c" @#数字2
　　a(2,2) = "0x66"
　　a(2,3) = "0x60"
　　a(2,4) = "0x60"
　　a(2,5) = "0x30"
　　a(2,6) = "0x18"
　　a(2,7) = "0x0c"
　　a(2,8) = "0x06"
　　a(2,9) = "0x06"
　　a(2,10)= "0x7e"
　　a(3,1) = "0x3c" @#数字3
　　a(3,2) = "0x66"
　　a(3,3) = "0xc0"
　　a(3,4) = "0x60"
　　a(3,5) = "0x1c"
　　a(3,6) = "0x60"
　　a(3,7) = "0xc0"
　　a(3,8) = "0xc0"
　　a(3,9) = "0x66"
　　a(3,10)= "0x38"
　　a(4,1) = "0x38" @#数字4
　　a(4,2) = "0x3c"
　　a(4,3) = "0x36"
　　a(4,4) = "0x33"
　　a(4,5) = "0x33"
　　a(4,6) = "0x33"
　　a(4,7) = "0xff"
　　a(4,8) = "0x30"
　　a(4,9) = "0x30"
　　a(4,10)= "0xfe"
　　a(5,1) = "0xfe" @#数字5
　　a(5,2) = "0xfe"
　　a(5,3) = "0x06"
　　a(5,4) = "0x06"
　　a(5,5) = "0x3e"
　　a(5,6) = "0x60"
　　a(5,7) = "0xc0"
　　a(5,8) = "0xc3"
　　a(5,9) = "0x66"
　　a(5,10)= "0x3c"
　　a(6,1) = "0x60" @#数字6
　　a(6,2) = "0x30"
　　a(6,3) = "0x18"
　　a(6,4) = "0x0c"
　　a(6,5) = "0x3e"
　　a(6,6) = "0x63"
　　a(6,7) = "0xc3"
　　a(6,8) = "0xc3"
　　a(6,9) = "0x66"
　　a(6,10) ="0x3c"
　　a(7,1) = "0xff" @#数字7
　　a(7,2) = "0xc0"
　　a(7,3) = "0x60"
　　a(7,4) = "0x30"
　　a(7,5) = "0x18"
　　a(7,6) = "0x18"
　　a(7,7) = "0x18"
　　a(7,8) = "0x18"
　　a(7,9) = "0x18"
　　a(7,10)= "0x18"
　　a(8,1) = "0x3c" @#数字8
　　a(8,2) = "0x66"
　　a(8,3) = "0xc3"
　　a(8,4) = "0x66"
　　a(8,5) = "0x3c"
　　a(8,6) = "0x66"
　　a(8,7) = "0xc3"
　　a(8,8) = "0xc3"
　　a(8,9) = "0x66"
　　a(8,10)= "0x3c"
　　a(9,1) = "0x3c" @#数字9
　　a(9,2) = "0x66"
　　a(9,3) = "0xc3"
　　a(9,4) = "0xc3"
　　a(9,5) = "0x66"
　　a(9,6) = "0x3c"
　　a(9,7) = "0x18"
　　a(9,8) = "0x0c"
　　a(9,9) = "0x06"
　　a(9,10)= "0x03"
　　%>