/* ==============================================================================
==============================================================================
*/
using System;
using System.IO;
using System.Linq;
using System.Collections.Generic;
public static class Program
{
public static void Main()
{
ParameterlessProperties.Go();
AnonymousTypesAndTuples.Go();
BitArrayTest();
}
private static void BitArrayTest()//P215 索引器调用
{
// 分配行14个位的bitarray数组
BitArray ba = new BitArray(14);
// 调用set访问器方法，将编号为偶数的所有位都设为true
for (Int32 x = 0; x < 14; x++)
{
ba[x] = (x % 2 == 0);
}
// 调用get访问器方法显示所有位的状态
for (Int32 x = 0; x < 14; x++)
{
Console.WriteLine("Bit " + x + " is " + (ba[x] ? "On" : "Off"));
}
}
}
internal static class ParameterlessProperties
{
public static void Go()
{
Employee emp = new Employee();
emp.Name = "Jeffrey Richter";
emp.Age = 45; //设置年龄
Console.WriteLine("Employee info: Name = {0}, Age = {1}", emp.Name, emp.Age);
try
{
emp.Age = -5; //抛出异常
}
catch (ArgumentOutOfRangeException e)
{
Console.WriteLine(e);
}
Console.WriteLine("Employee info: Name = {0}, Age = {1}", emp.Name, emp.Age);
}
private sealed class Employee
{
private String m_Name; // 字段现在是私有的
private Int32 m_Age; // 字段现在是私有的
public String Name
{
get { return (m_Name); }
set { m_Name = value; } // 关键字values总是代表新值
}
public Int32 Age
{
get { return (m_Age); }
set
{
if (value <= 0) // // 关键字values总是代表新值
throw new ArgumentOutOfRangeException("value", "must be >0");
m_Age = value;
}
}
}
}
internal static class AnonymousTypesAndTuples
{
public static void Go()
{
AnonymousTypes();
TupleTypes();
Expando();
}
private static void AnonymousTypes()//P209
{
// 定义类型，构造实例，并初始化属性
var o1 = new { Name = "Jeff", Year = 1964 };
// 在控制台上显示属性：Name=Jeff,Year=1964
Console.WriteLine("Name={0}, Year={1}", o1.Name, o1.Year);
String Name = "Grant";
DateTime dt = DateTime.Now;
var o2 = new { Name, dt.Year };
ShowVariableType(o1);
ShowVariableType(o2);
Console.WriteLine("Types are same: " + (o1.GetType() == o2.GetType()));
// 一个类型允许相等测试和赋值操作
Console.WriteLine("Objects are equal: " + o1.Equals(o2));
o1 = o2; // 赋值
var people = new[] {
o1,
new { Name = "Kristin", Year = 1970 },
new { Name = "Aidan", Year = 2003 },
new { Name = "Grant", Year = 2008 }
};
foreach (var person in people)
Console.WriteLine("Person={0}, Year={1}", person.Name, person.Year);
String myDocuments = Environment.GetFolderPath(Environment.SpecialFolder.MyDocuments);
var query =
from pathname in Directory.GetFiles(myDocuments)
let LastWriteTime = File.GetLastWriteTime(pathname)
where LastWriteTime > (DateTime.Now - TimeSpan.FromDays(7))
orderby LastWriteTime
select new { Path = pathname, LastWriteTime };
foreach (var file in query)
Console.WriteLine("LastWriteTime={0}, Path={1}", file.LastWriteTime, file.Path);
}
private static void ShowVariableType<T>(T t) { Console.WriteLine(typeof(T)); }
/************ System.Tupele 类型 **********************/
//用Item1返回最小值&用Item2返回最大值
private static Tuple<Int32, Int32> MinMax(Int32 a, Int32 b)
{
return Tuple.Create(Math.Min(a, b), Math.Max(a, b));
//return new Tuple<Int32, Int32>(Math.Min(a, b), Math.Max(a, b));
}
// 下面展示了如何调用方法，以及如何使用返回的Tuple
private static void TupleTypes()//P213
{
var minmax = MinMax(6, 2);
Console.WriteLine("Min={0}, Max={1}", minmax.Item1, minmax.Item2);
var t = Tuple.Create(0, 1, 2, 3, 4, 5, 6, Tuple.Create(7, 8));
Console.WriteLine("{0}, {1}, {2}, {3}, {4}, {5}, {6}, {7}, {8}",
t.Item1, t.Item2, t.Item3, t.Item4, t.Item5, t.Item6, t.Item7,
t.Rest.Item1.Item1, t.Rest.Item1.Item2);
}
private static void Expando()//P214
{
dynamic e = new System.Dynamic.ExpandoObject();
e.x = 6; // 添加一个Int32 ‘x’属性，其值为6
e.y = "Jeff"; // 添加一个String ‘y’属性，其值为Jeff
e.z = null; // 添加一个object‘z’属性，其值为null
// 查看所有属性及其值：
foreach (var v in (IDictionary<String, Object>)e)
Console.WriteLine("Key={0}, V={1}", v.Key, v.Value);
// 删除x属性及其值；
((IDictionary<String, Object>)e).Remove("x");
}
}
internal sealed class BitArray//P(214)
{
//容纳了二进制为的私有字节数组
private Byte[] m_byteArray;
private Int32 m_numBits;
// 下面构造器用于分配字节数组，并将所有位设为0
public BitArray(Int32 numBits)
{
// 先验证实参
if (numBits <= 0)
throw new ArgumentOutOfRangeException("numBits must be > 0");
// 保存位的个数
m_numBits = numBits;
//为位数组分配字节
m_byteArray = new Byte[(m_numBits + 7) / 8];
}
// 下面是索引器（有参属性）
public Boolean this[Int32 bitPos]
{
// 下面是索引器的get访问器方法
get
{
// 先验证实参
if ((bitPos < 0) || (bitPos >= m_numBits))
throw new ArgumentOutOfRangeException("bitPos", "bitPos must be between 0 and " + m_numBits);
// 返回指定索引处的位的状态
return ((m_byteArray[bitPos / 8] & (1 << (bitPos % 8))) != 0);
}
// 下面是索引器的set访问器方法
set
{
if ((bitPos < 0) || (bitPos >= m_numBits))
throw new ArgumentOutOfRangeException("bitPos", "bitPos must be between 0 and " + m_numBits);
if (value)
{
// 将指定索引处的位设为ture
m_byteArray[bitPos / 8] = (Byte)
(m_byteArray[bitPos / 8] | (1 << (bitPos % 8)));
}
else
{
//将指定索引处的位设为false
m_byteArray[bitPos / 8] = (Byte)
(m_byteArray[bitPos / 8] & ~(1 << (bitPos % 8)));
}
}
}
}
