c# - An object reference is required for the non-static field -

i have followed this tutorial , try use access database in c# console application.

i have 2 classes:

class ac     {         oledbconnection connection;         oledbcommand command;          private void connectto()         {             connection = new oledbconnection(@"provider=microsoft.ace.oledb.15.0;data source=d:\info\csharp\socket\ef\accesstest\accesstest\bin\debug\database.accdb;persist security info=false");             command = connection.createcommand();         }          public ac()         {             connectto();         }          public void insert(string a, string b)         {             try             {                 command.commandtext = "insert persons (nname, nnamee) values (\"" + + "\", \"" + b + "\");";                 command.commandtype = system.data.commandtype.text;                 connection.open();                  command.executenonquery();             }             catch (exception)             {                 throw;             }                         {                 if (connection != null)                 {                     connection.close();                 }             }         }     } 

and,

namespace accesstest {     public class mainclass     {         ac f = new ac();          public static void main()         {             f.insert("ab", "ac");              console.writeline("\n\npress enter close...");             console.readline();         }     } } 

and "an object reference required non-static field, method, or property 'accesstest.mainclass.f'". try remove static from, don't work, main must pe static.

any ideas me ? thank !

you can't refer instance variable f without object reference in static context.

as per msdn,the main method entry point of program; program control starts , ends.

• main declared inside class or struct. main must static , should not public. (in earlier example, receives default access of private.) enclosing class or struct not required static.
• main can either have void or int return type.
• the main method can declared or without string[] parameter contains command-line arguments. when using visual studio create windows forms applications, can add parameter manually or else use environment class obtain command-line arguments. parameters read zero-indexed command-line arguments. unlike c , c++, name of program not treated first command-line argument.

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