一.
１.不能仅使用params来重载方法
2.不允许out,ref和params同时使用
3.params数组必须是最后一个参数
4.一个没有params的方法的优先级要高于带params的方法
5.对于引起歧义的方法重载，编译器会报错.
eg:public static int Min(params int[] paramsList)
public statc int Min(int i,params int[] paramsList )
//complie-time error
Console Demo
Util.cs
using System; using System.Collections.Generic; using System.Linq; using System.Text; namespace ParamsDemo { class Util { /* public static int Min(int[] paramList) { if (paramList == null || paramList.Length == 0) { throw new ArgumentException("Uintil.Min:Not enougn arguments"); } int currentMin = paramList[0]; foreach (int i in paramList) { if (i < currentMin) { currentMin = i; } } return currentMin; } */ public static int Min( params int[] paramList) { if (paramList == null || paramList.Length == 0) { throw new ArgumentException( " Uintil.Min:Not enougn arguments "); } int currentMin = paramList[ 0]; foreach ( int i in paramList) { if (i < currentMin) { currentMin = i; } } return currentMin; } } }
2.Program.cs
using System; using System.Collections.Generic; using System.Linq; using System.Text; namespace ParamsDemo { class Program { static void Main( string[] args) { /* int[] intArray = new int[2] { 55, 66 }; int min=Util.Min(intArray); Console.WriteLine(min); Console.WriteLine("------------------------"); int[] intArraY1 = new int[8] { 11, 33, 55, 8, 22, 10, 77, 88 }; int min1 = Util.Min(intArraY1); Console.WriteLine(min1); */ int min1 = Util.Min( 100, 200, 300, 80, 90, 5, 90); Console.WriteLine(min1); } } }
二.
使用params object 数组
class Black{
public static void Hole(params object[] paramList)
}
代表Hole这个方法能接收任意参数
1,可能不给此方法传递任何参数
Black.Hole()
2.可以传递null参数
Black.Hole(null);
3.可以传递一个精确的数组
object[] array=new object(2);
array[0]="forty two";
array[1]=42;
Black.Hole(array);
4,可以传递不同为型的参数
Black.Hole("forty two",42);
//converted to Black.Hole(new object[]{"forty two",42});
Console Demo
Util.cs
using System; using System.Collections.Generic; using System.Linq; using System.Text; namespace ParamsArray { class Util { public static int Sum( params int[] paramsList) // 任意长度的参数个数 { Console.WriteLine( " Using parameter list "); if (paramsList == null) { throw new ArgumentException( " Util.Sum:null parameters in paramsList "); } if (paramsList.Length == 0) { throw new ArgumentException( " Util.Sum:empty paramsList "); } int sumTotal = 0; foreach ( int i in paramsList) { sumTotal += i; } return sumTotal; } public static int Sum( int parm1= 0, int parm2= 0, int parm3= 0, int parm4= 0) // 最多只能传递４个整型参数(可选参数类型) { Console.WriteLine( " Using optional parameters "); int sumTotal = parm1 + parm2 + parm3 + parm4; return sumTotal; } } }
Program.cs
using System; using System.Collections.Generic; using System.Linq; using System.Text; namespace ParamsArray { class Program { static void Main( string[] args) { try { DoWork(); } catch (Exception ex) { Console.WriteLine( " Exception:{0} ",ex.Message); } } static void DoWork() { // Console.WriteLine(Util.Sum(null)); // Console.WriteLine(Util.Sum()); Console.WriteLine(Util.Sum( 10, 9, 8, 7, 6, 5, 4, 3, 2, 1)); Console.WriteLine(Util.Sum( 2, 4, 6, 8)); Console.WriteLine(Util.Sum( 2, 4, 6)); // 前三个参数赋值，后一个参数取默认值。此函数优先级高于带params的函数. Console.WriteLine(Util.Sum( 2, 4, 6, 8, 10)); // 调用的是带params的函数 } } }