C#语言学习--基础部分(十八)数组参数

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　
        }

    }
}