Index was outside the bounds of the array.

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C#

public string generateSNo()
       {
           String str = "SELECT Max(std_ID) From tblStudent";
           string std_ID = null;
           SqlCommand con = new SqlCommand(str, cn);
           cn.Open();

           if (con.ExecuteScalar().Equals(DBNull.Value))
           {
               std_ID = "S001";
           }
           else
           {
               std_ID = (string)con.ExecuteScalar();

               //Display the new stdno (by get the last stdno from db)+1
               string[] splitCode = Strings.Split(std_ID, "S", 2);
               std_ID = "S00" + ((Convert.ToInt32(splitCode[1])) + 1).ToString();
           }

           cn.Close();
           return std_ID;
       }

Posted 17-Dec-14 18:34pm

Member 11308948

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vishal.shimpi 18-Dec-14 1:03am

Have you checked, what will be the value in splitCode[1]? do check this it might be helpful for you.

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Raul Iloc · Accepted Answer · 2014-12-17T18:48:00

Solution 1

1. The error is generated by the fact that you are expecting that the Split to gave you 2 results, but in your case its return only one string like "001".

2.Other problem is that you are running the same SqlCommand twice, so you should modify your code like below:

C#

public string generateSNo()
       {
           String str = "SELECT Max(std_ID) From tblStudent";
           string std_ID = null;
           SqlCommand con = new SqlCommand(str, cn);
           cn.Open();
           object result = con.ExecuteScalar();
           if (result == DBNull.Value)
           {
               std_ID = "S001";
           }
           else
           {
               std_ID= (string)result;
               string[] splitCode = std_ID.Split(new char[]{'S'}, 2, StringSplitOptions.RemoveEmptyEntries);
               int id = 0;
               int.TryParse(splitCode[0], out id);
               id++;
               std_ID = string.Format("S{0:D3}", id); //To have values like: S001, S002, ..., S099, ..., S999!
           }
 
           cn.Close();
           return std_ID;
       }

Posted 17-Dec-14 18:48pm

Raul Iloc

Updated 17-Dec-14 19:27pm

v6

Comments

Member 11308948 18-Dec-14 0:51am

is there any solution because i applied the same method for generate feedback no its work perfectly but to generate student no its showing error

Raul Iloc 18-Dec-14 0:55am

See my update above!

Member 11308948 18-Dec-14 1:00am

Input string was not in a correct format.

Raul Iloc 18-Dec-14 1:06am

Did you debug your code?
What is the value of the ID that is read from the database? It is like "S001"?

Member 11308948 18-Dec-14 1:13am

im getting the error

Raul Iloc 18-Dec-14 1:16am

See my update now!

Member 11308948 18-Dec-14 1:18am

:'(
now this error Object reference not set to an instance of an object.

Member 11308948 18-Dec-14 1:19am

I did this for generate feedback no it's working perfectly
public string generateFNo()
{
String str = "SELECT Max(fdk_No) From tblFeedback";
string fNo = null;
SqlCommand con = new SqlCommand(str, cn);
cn.Open();

if (con.ExecuteScalar().Equals(DBNull.Value))
{
fNo = "F01";
}
else
{
fNo = (string)con.ExecuteScalar();

//Display the new fdkno (by get the last fdkno from db)+1
string[] splitCode = Strings.Split(fNo, "F", 2);
fNo = "F0" + ((Convert.ToInt32(splitCode[1])) + 1).ToString();
}

cn.Close();
return fNo;
}

Raul Iloc 18-Dec-14 1:24am

Sorry I copy and paste from my test and I delete a line a code. By now should work!
You could test now!

Member 11308948 18-Dec-14 1:44am

thank your sir.problem solved

Raul Iloc 18-Dec-14 1:59am

Welcome, I glad that I could help you!

Member 11308948 18-Dec-14 2:07am

sir , now its run and the id is generated but
once i save it shows the connection not closed when i already con.close()

Raul Iloc 18-Dec-14 2:14am

You should close your connection into the "finally" section of a try-finally block!

Member 11308948 18-Dec-14 2:26am

is it like this sir?

public string generateSNo()
{
String str = "SELECT Max(std_ID) From tblStudent";
string std_ID = null;
SqlCommand con = new SqlCommand(str, cn);
try
{
cn.Open();
object result = con.ExecuteScalar();
if (result == DBNull.Value)
{
std_ID = "S001";
}
else
{

std_ID = (string)result;
string[] splitCode = std_ID.Split('S');
int id = 0;
int.TryParse(splitCode[0], out id);
id++;
std_ID = string.Format("S{0:D3}", id); //To have values like: S001, S002, ..., S099, ..., S999!

}
}

finally
{
cn.Close();
}

return std_ID;
}

Raul Iloc 18-Dec-14 4:12am

1.It seems that your connection object is created at the class level and could remain open from other methods, better is to use a local variable.

2.In your code above, if you want to reuse an open connection, you should test if is already open by using "if(cn.State == ConnectionState.Open)" and not to open in this case.