C # method Note 1: C #4.0 new features: named parameters and optional parameters

Before C #4.0, to call a method, you must strictly follow the number, type, or even parameter sequence and method. But this problem can be solved in C #4.0.   1. optional parameter. It can be understood as two situations: ① if a parameter is not specified, a default value is given. ② If the parameter value is specified, the default value is not used. In this way, you do not need to judge every time or write a heavy-load function. CodeAs follows:

 Class  Program {  Static   Void Main ( String  [] ARGs) {program Program =New  Program ();  Int M = program. Add ( 10 ); //  Here M = 11; default B = 1;              Int N = program. Add ( 10 , 20 ); //  Here n = 30; Where B = 20;  }  Public   Int Add ( Int A, Int B = 1  ){  Return A + B; //  If the value of B is not specified when a function is called, the default value is 1;  }} 

 

    2. Name Parameters Optional parameters solve the default value of parameters, while named parameters solve the order of parameters. We generally determine the order of parameters when a method is called according to the parameter sequence when the method is defined, for example:    

  Class  Program {  Static   Void Main ( String  [] ARGs) {program Program = New  Program ();  Int M = 5  ;  Int N = 30 ;  Int Result = program. getlastnum (Y: n, x: m ); //  Note. The interchange between the positions of X and Y.  //  Not in the order required by the Method  }  Public   Int Getlastnum ( Int X, Int  Y ){  If (X <Y ){  Return  X ;}  Return   0  ;}