验证码制作之二：可选择位数的字符与数字混合码

using System; using System.Data; using System.Configuration; using System.Web; using System.Web.Security; using System.Web.UI; using System.Web.UI.WebControls; using System.Web.UI.WebControls.WebParts; using System.Web.UI.HtmlControls; /// <summary> /// randomCode 的摘要说明 /// </summary> public class randomCode { public randomCode() { // // TODO: 在此处添加构造函数逻辑 // } /// <summary> /// 验证码 /// </summary> /// <param name="n">验证码的个数</param> /// <returns>返回生成的随机数</returns> public string RandomNum(int n) // { string strchar = "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,V,W,X,Y,Z,a,b,c,d,e,f,g,h,i,j,k,l,m,n,o,p,q,r,s,t,u,v,w,x,y,z"; string[] VcArray = strchar.Split(','); string VNum = ""; // int temp = -1; //记录上次随机数值，尽量避免产生几个一样的随机数 //采用一个简单的算法以保证生成随机数的不同 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(61); if (temp != -1 && temp == t) { return RandomNum(n); } temp = t; VNum += VcArray[t]; } return VNum;//返回生成的随机数 } }