automatic code generation in a textbox

String[] ar={"a","b","c","d","e","f","g","h","z","0","1","2","3","9"};

//put all alphanumeric in above array

Random myrandom = new Random();

String userid="";

for(int i=0;i<10;i++)

{

  int index = myrandom.Next(0,ar.Length); 

  userid=userid+ar[index];

}

now userid have combined string of 10 randomly generated value.

ok thanks vimal.

Combining the random numbers from an array means :declaring an array of type string and storing all alphabets and digits in it? could you please show me how to do that?

Sachi,Upto my knowledge there is no built in function for alphanumeric.

check out below link
http://www.c-sharpcorner.com/Forums/ShowMessages.aspx?ThreadID=57332

in my answer,
 in array, you add all alphabetic and numeric values
and get 10 random values from that and combine it.

and we cant get Random no for 10 digit.because it accepts upto 9 digit.if you need 10 digit then you can prefix a digit with the result.

Hi Sachi,

For Random no Generation

Random rnd = new Random();
int userid=rnd.Next(min no, max no);

if you need a 8 digit code as user id then
give min no-10000000
give max no-99999999

and for duplicate entry checking, i have an idea, but it may not best idea.

you just use a select statement.something like
select * from urtable where userid=generated no

if it return empty dataset i.e with 0 rows or null
then its not available.you can insert a new entry with this no

if it return a row then you generate another no and check it with database.