asp .NET登錄界面用戶驗證碼代碼

//ASP .NET用戶登錄界面經常用到驗證碼代碼如下PRivate void Page_Load(object sender, System.EventArgs e){// 在此處放置用戶代碼以初始化頁面Label4.Text=RandomNum(4);}public string RandomNum(int n) //{string strchar = "0,1,2,3,4,5,6,7,8,9" ;string[] VcArray = strchar.Split(',') ;string VNum = "" ;//由于字符串很短，就不用StringBuilder了int temp = -1 ; //記錄上次隨機數值，盡量避免產生幾個一樣的隨機數//采用一個簡單的算法以保證生成隨機數的不同Random rand =new Random();for ( int i = 1 ; i < n+1 ; i++ ) { if ( temp != -1) {rand =new Random(i*temp*unchecked((int)DateTime.Now.Ticks));} //int t = rand.Next(35) ;int t=rand.Next(10);if (temp != -1 && temp == t) {return RndNum( n);}temp = t ;VNum += VcArray[t];}return VNum ;//返回生成的隨機數}// ''函數名稱:RndNum // ''函數參數:VCodeNum--設定返回隨機字符串的位數 // ''函數功能:產生數字和字符混合的隨機字符串 private string RndNum(int VcodeNum) { string Vchar = "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[] VcArray = Vchar.Split(",".ToCharArray()); //將字符串生成數組 string VNum = ""; int i; for(i=1;i<VcodeNum;i++) { System.Random ro = new Random(); double decA = ro.NextDouble(); VNum = VNum + VcArray[Convert.ToInt32(35*decA)]; } // For i=1 to VcodeNum // Randomize // VNum=VNum & VcArray(Int(35*Rnd)) ''數組一般從0開始讀取，所以這里為35*Rnd // Next return VNum; }//ASP .NET登錄界面用戶驗證碼代碼，網絡上搜集整理測試