params 修饰符

《C# 与 .NET 4高级程序设计》读书笔记

params关键字可以把可变数量的相同类型参数作为单个逻辑参数传给方法。

调用者可以传入强类型数组或以逗号分隔的项列表。

using System;

namespace Test
{
    class Program
    {
        static double CalculateAverage(params double[] values)
        {
            Console.WriteLine("You sent me {0} doubles.", values.Length);

            double sum = 0;
            if (values.Length == 0)
            {
                return sum;
            }

            for (int i = 0; i < values.Length; i++)
            {
                sum += values[i];
            }
            return (sum / values.Length);
        }

        static void Main(string[] args)
        {
            Console.WriteLine("***** Fun with Methods *****");

            // 传递一个以逗号分隔的double型数的列表
            double average;
            average = CalculateAverage(4.0, 3.2, 5.7, 64.2, 87.2);
            Console.WriteLine("Average of data is: {0}", average);

            //传递一个double型的数组
            double[] data = { 4.0, 3.2, 5.7 };
            average = CalculateAverage(data);
            Console.WriteLine("Average of data is: {0}", average);

            // 0的平均值是0
            Console.WriteLine("Average of data is: {0}", CalculateAverage());
            Console.ReadLine();
        }
    }
}