Linq中的Aggragate的使用

演示1：用于累加：

这是用Aggragate方法的案例：

  public static void AggragateAccumulation()        {            int[] array = { 1, 2, 3, 4, 5, 6 };            /*             * 1+2=3;             * 3+3=6;             * 6+4=10;             * 10+5=15;             * 15+6=21;             */            int result = array.Aggregate((a, b) => a + b);            Console.WriteLine("累加的结果是：{0}",result);                    }
用普通方法累加：
public static void Accumulation()        {            int[] array = { 1, 2, 3, 4, 5, 6 };            int result = 0;            foreach (int i in array)                result += i;            Console.WriteLine("累加的结果是：" + result);        }
演示2：IEnumeraber<int>用于阶乘：
public static void AggregateFactorial()        {            var numbers = IntArray(6);            //1*2=2;            //2*3=6;            //6*4=24;            //24*5=120;            //120*6=720;            var result = numbers                .Select(n => n)                .Aggregate((total, next) =>                {                    return total * next;                });                       Console.WriteLine("6的阶乘是：{0}", result);        }PRivate static IEnumerable<int> IntArray(int max)        {            List<int> result = new List<int>();            for (int i = 0; i < max; i++)                result.Add(i + 1);            return result;        }
用普通方法计算阶乘：
 public static void Factorial()        {            var ints = IntArray(6);            int result = 1;//注意这是初始值为1            foreach (var i in ints)                result *= i;            Console.WriteLine("6的阶乘的是：{0}", result);        }
int[]数组用于阶乘：
public static void AggregateArrFactorial()        {            int[] array = { 1, 2, 3, 4, 5, 6 };            int result = array.Aggregate((a, b) => a * b);            Console.WriteLine("6的阶乘是：{0}",result);        }        public static void ArrayFactorial()        {            int[] array = { 1, 2, 3, 4, 5, 6 };            int result = 1;            foreach (var i in array)                result *= i;            Console.WriteLine("6的阶乘是：{0}", result);        }
 演示3：string[]用于字符串数组的反转
public static void AggragateReverse()        {            string city = "GuangZhou,ZhuHai,ShenZhen,ChangSha,ChangDe";            string[] cities = city.Split(',');            string newCity = cities                .Aggregate((currentCity, nextCity) => nextCity + " " + currentCity);            string aa="aaa";                      Console.WriteLine("反转后的城市为：{0}", newCity);        }
 用普通方法计算字符串数组反转：
public static void ReverseCity()        {            string city = "GuangZhou,ZhuHai,ShenZhen,ChangSha,ChangDe";            string[] cities = city.Split(',');            string newCity = "";            for (int i = cities.Length - 1; i >= 0; i--)                newCity += cities[i] + " ";            Console.WriteLine("反转后的城市为：{0}", newCity);        }
 
 演示4：应用累加器函数和结果选择器
  public static void AggragateSelector()        {            string[] fruits = { "apple", "mango", "pear", "avocado", "banana", "watermelon", "passionfruit", "grape" };            string lonestFruit = fruits                .Aggregate("avocado",                (longest, next) => next.Length > longest.Length ? next : longest,                fruit => fruit.ToUpper());            Console.WriteLine("名字最长的水果是：{0}", lonestFruit);        }
用普通方法演示上例，代码如下：
public static void LongestFruit()        {            string[] fruits = { "apple", "mango", "pear", "avocado", "banana", "watermelon", "grape", "passionfruit"};            string longestFruit = "";            for (int i = 0; i < fruits.Length; i++)            {                for (int j = i + 1; j < fruits.Length; j++)                {                    int fruitLength = fruits[i].Length;                    int nextFruitLength = fruits[j].Length;                    if (nextFruitLength > fruitLength)                        longestFruit = fruits[j];                    else                        longestFruit = fruits[i];                }            }            Console.WriteLine("名字最长的水果是：{0}", longestFruit.ToUpper());        }
 各位同仁，如果有更好的方法，大家可以进行讨论，这里没有给出各个两种方式的效率的对比。大家可以自行比较。