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　
}

}
}