c# - Method error, with mysql -

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• what nullreferenceexception, , how fix it? 29 answers

i have coded function following, , getting error, trying items details db method returns string.

    public static string getitemdetails(int i_id, string i_name)     {         mysqlconnection sql_con = new mysqlconnection(vpconfig.sql_conns);         string[] itemdata = null;         i_name = i_name == null ? string.empty : i_name;         i_id = i_id == 0 ? 0 : i_id;          try         {             if(i_id != 0)             {                 //get item details id                 string query = "select * items id="+i_id;                 mysqlcommand xv = new mysqlcommand(query, sql_con);                 sql_con.open();                 mysqldatareader rdr = xv.executereader();                 while(rdr.read())                 {                     itemdata[0] = rdr.getstring("id");                     itemdata[1] = rdr.getstring("iname");                     itemdata[2] = rdr.getstring("iprice");                 }                 sql_con.close();                  string master = itemdata[0] +"*"+ itemdata[1] +"*"+ itemdata[2];                  return master;//return format id*name*price             }             else if(i_name != string.empty)             {                 //get item details name                 string query = "select * items iname=" + i_name;                 mysqlcommand xv = new mysqlcommand(query, sql_con);                 sql_con.open();                 mysqldatareader rdr = xv.executereader();                 while (rdr.read())                 {                     itemdata[0] = rdr.getstring("id");                     itemdata[1] = rdr.getstring("iname");                     itemdata[2] = rdr.getstring("iprice");                 }                 sql_con.close();                  string master = itemdata[0] + "*" + itemdata[1] + "*" + itemdata[2];                  return master;//return format id*name*price             }             else             {                 messagebox.show("no items! found id/name: " + i_id + i_name);             }              //if nothing             return null;         }         catch(exception ex)         {             messagebox.show("error code: 17 "+ex.message);              //if nothing             return null;         } 

now, if pass following argument showing error "error code :17 object reference not set instance of object." catch,

string xv = vpfunctions.getitemdetails(5, string.empty); ta.text = xv; 

thank you.

the exception thrown because declared string array null , assign value in datareader loop.

so, line:

string[] itemdata = null; 

should changed this:

string[] itemdata = new string[5];