【例4.1】设计一个控制台应用程序，采用二分查找方法在给定的有序数组a中查找用户输入的值，并提示相应的查找结果。

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;namespace ConsoleApplication3
{class Program{static void Main(string[] args){double[] a = new double[10]{ 0, 1, 2, 3, 4, 5, 6, 7, 8, 9};double k;int low = 0, high = 9, mid;Console.Write("k:");k = double.Parse(Console.ReadLine());while(low<high){mid = (low + high) / 2;if (a[mid] == k){Console.WriteLine("a[{0}]={1}", mid, k);Console.ReadLine();return;}else if (a[mid] > k) high = mid - 1;else low = mid + 1;}Console.WriteLine("未找到{0}", k);Console.ReadLine();}}
}

【例4.2】设计一个控制台应用程序，输出9行杨辉三角形。

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;namespace ConsoleApplication3
{class Program{const int N = 10;static void Main(string[] args){int i, j;int[,]a=new int[N,N];for (i = 1; i < N;i++ ){a[i, i] = 1;a[i, 1] = 1;}for (i = 3; i < N;i++ )for (j = 2; j <= i-1;j++ )a[i,j]=a[i-1,j-1]+a[i-1,j];for (i = 1; i < N; i++) {for (j = 1; j <= i; j++) Console.Write("{0,-3}",a[i,j]);Console.WriteLine();}Console.ReadLine();}}
}