c# - CIL OpCode (Ldarg_0) is used even though there are no arguments -

i have following c# code.

public void helloworld() {     add(2, 2); }  public void add(int a, int b) {     //do } 

it produces following cil

.method public hidebysig instance void  helloworld() cil managed {   // code size       11 (0xb)   .maxstack  8   il_0000:  nop   il_0001:  ldarg.0   il_0002:  ldc.i4.2   il_0003:  ldc.i4.2   il_0004:  call       instance void consoleapplication3.program::add(int32,                                                                       int32)   il_0009:  nop   il_000a:  ret } // end of method program::helloworld 

now, don't understand line @ offset 0001:

ldarg.0

i know opcode for, don't understand why it's being used in method, there no arguments, right?

does know why? :)

in instance methods there implicit argument index 0, representing instance on method invoked. can loaded on il evaluation stack using ldarg.0 opcode.