csharp: Use of Is and As operators in csharp

/// <summary>
/// Geovin Du 20170622
/// </summary>
/// <param name="sender"></param>
/// <param name="e"></param>
private void button1_Click(object sender, EventArgs e)
{
Object o = new Object();
System.Boolean b1 = (o is System.Object);//b1 为true
System.Boolean b2 = (o is Employee);//b2为false

if (o is Employee)
{
Employee em = (Employee)o;
em.RealName = "geovindu";
MessageBox.Show(em.RealName);
}
else
{
MessageBox.Show("no"); //结果为显示NO
}
Object obj;
Employee employee = new Employee();
employee.RealName = "du";
employee.Birthday = DateTime.Now;
employee = o as Employee;
obj = o as Employee;

if (employee != null)
{
//在if语句中使用e
MessageBox.Show(employee.RealName);
}
else
{
MessageBox.Show("no2");  //结果为显示NO2
}

}
/// <summary>
///
/// </summary>
/// <param name="sender"></param>
/// <param name="e"></param>
private void button2_Click(object sender, EventArgs e)
{
var c1 = "";
var c2 = typeof(string);
object oc1 = c1;
object oc2 = c2;

var s1 = 0;
var s2 = '.';
object os1 = s1;
object os2 = s2;

bool b = false;

Stopwatch sw = Stopwatch.StartNew();
for (int i = 0; i < 10000000; i++)
{
b = c1.GetType() == typeof(string); // ~60ms
b = c1 is string; // ~60ms

b = c2.GetType() == typeof(string); // ~60ms
b = c2 is string; // ~50ms

b = oc1.GetType() == typeof(string); // ~60ms
b = oc1 is string; // ~68ms

b = oc2.GetType() == typeof(string); // ~60ms
b = oc2 is string; // ~64ms

b = s1.GetType() == typeof(int); // ~130ms
b = s1 is int; // ~50ms

b = s2.GetType() == typeof(int); // ~140ms
b = s2 is int; // ~50ms

b = os1.GetType() == typeof(int); // ~60ms
b = os1 is int; // ~74ms

b = os2.GetType() == typeof(int); // ~60ms
b = os2 is int; // ~68ms

b = GetType1<string, string>(c1); // ~178ms
b = GetType2<string, string>(c1); // ~94ms
b = Is<string, string>(c1); // ~70ms

b = GetType1<string, Type>(c2); // ~178ms
b = GetType2<string, Type>(c2); // ~96ms
b = Is<string, Type>(c2); // ~65ms

b = GetType1<string, object>(oc1); // ~190ms
b = Is<string, object>(oc1); // ~69ms

b = GetType1<string, object>(oc2); // ~180ms
b = Is<string, object>(oc2); // ~64ms

b = GetType1<int, int>(s1); // ~230ms
b = GetType2<int, int>(s1); // ~75ms
b = Is<int, int>(s1); // ~136ms

b = GetType1<int, char>(s2); // ~238ms
b = GetType2<int, char>(s2); // ~69ms
b = Is<int, char>(s2); // ~142ms

b = GetType1<int, object>(os1); // ~178ms
b = Is<int, object>(os1); // ~69ms

b = GetType1<int, object>(os2); // ~178ms
b = Is<int, object>(os2); // ~69ms
}

sw.Stop();
MessageBox.Show(sw.Elapsed.TotalMilliseconds.ToString());
}
/// <summary>
///
/// </summary>
/// <typeparam name="S"></typeparam>
/// <typeparam name="T"></typeparam>
/// <param name="t"></param>
/// <returns></returns>
static bool GetType1<S, T>(T t)
{
return t.GetType() == typeof(S);
}
/// <summary>
///
/// </summary>
/// <typeparam name="S"></typeparam>
/// <typeparam name="T"></typeparam>
/// <param name="t"></param>
/// <returns></returns>
static bool GetType2<S, T>(T t)
{
return typeof(T) == typeof(S);
}
/// <summary>
///
/// </summary>
/// <typeparam name="S"></typeparam>
/// <typeparam name="T"></typeparam>
/// <param name="t"></param>
/// <returns></returns>
static bool Is<S, T>(T t)
{
return t is S;
}
/// <summary>
///
/// </summary>
/// <param name="sender"></param>
/// <param name="e"></param>
private void button3_Click(object sender, EventArgs e)
{
var cl1 = new Class1();
if (cl1 is IFormatProvider)
{
MessageBox.Show("cl1 is IFormatProvider ok");
}
else
{
MessageBox.Show("cl1 is IFormatProvider no");
}
if (cl1 is Object)
{
MessageBox.Show("cl1 is Object ok");
}
else
{
MessageBox.Show("cl1 is Object no");
}
if (cl1 is Class1)
{
MessageBox.Show("cl1 is Class1 ok");
}
else
{
MessageBox.Show("cl1 is Class1 no");
}
if (cl1 is Class2)
{
MessageBox.Show("cl1 is Class2 ok");
}
else
{
MessageBox.Show("cl1 is Class2 no");
}

var cl2 = new Class2();
if (cl2 is IFormatProvider)
{
MessageBox.Show("cl2 is IFormatProvider ok");
}
else
{
MessageBox.Show("cl2 is IFormatProvider no");
}
if (cl2 is Class2)
{
MessageBox.Show("cl2 is Class2 ok");
}
else
{
MessageBox.Show("cl2 is Class2 no");
}
if (cl2 is Class1)
{
MessageBox.Show("cl2 is Class1 ok");
}
else
{
MessageBox.Show("cl2 is Class1 no");
}

Class1 cl = cl2;
if (cl is Class1)
{
MessageBox.Show("cl is Class1 ok");
}
else
{
MessageBox.Show("cl is Class1 no");
};
if(cl is Class2)
{
MessageBox.Show("cl is Class2 ok");
}
else
{
MessageBox.Show("cl is Class2 no");
};

bool isc1 = (cl is Class1);
if (isc1)
{
MessageBox.Show("true");
}

}
/// <summary>
///
/// </summary>
/// <param name="sender"></param>
/// <param name="e"></param>
private void button4_Click(object sender, EventArgs e)
{
Object o = new Person("Jane");
ShowValue(o);

o = new Dog("Alaskan Malamute");
ShowValue(o);

Employee em = new Employee();
em.RealName = "geovindu";
em.Birthday = DateTime.Now;
o =em;
ShowValue(o);
}
/// <summary>
///
/// </summary>
/// <param name="o"></param>
public static void ShowValue(object o)
{
if (o is Person)
{
Person p = (Person)o;
MessageBox.Show(p.Name);
}
else if (o is Dog)
{
Dog d = (Dog)o;
MessageBox.Show(d.Breed);
}
else
{
MessageBox.Show("啥也不是");
}
}

}
/// <summary>
///
/// </summary>
public class Class1 : IFormatProvider
{
public object GetFormat(Type t)
{
if (t.Equals(this.GetType()))
return this;
return null;
}
}
/// <summary>
///
/// </summary>
public class Class2 : Class1
{
public int Value { get; set; }
}
/// <summary>
/// 员工
/// </summary>
public class Employee
{
/// <summary>
/// 真名
/// </summary>
public string RealName { set; get; }
/// <summary>
/// 出生日期
/// </summary>
public DateTime Birthday { set; get; }
}
/// <summary>
///
/// </summary>
public struct Person
{
public string Name { get; set; }

public Person(string name)
: this()
{
Name = name;
}
}
/// <summary>
///
/// </summary>
public struct Dog
{
public string Breed { get; set; }

public Dog(string breedName)
: this()
{
Breed = breedName;
}
}

/// <summary>
/// Geovin Du 涂聚文
/// </summary>
/// <param name="sender"></param>
/// <param name="e"></param>
private void button5_Click(object sender, EventArgs e)
{
Int32 indent = 0;
// Display information about each assembly loading into this AppDomain.
foreach (Assembly b in AppDomain.CurrentDomain.GetAssemblies())
{
Display(indent, "Assembly: {0}", b);

// Display information about each module of this assembly.
foreach (Module m in b.GetModules(true))
{
Display(indent + 1, "Module: {0}", m.Name);
}

// Display information about each type exported from this assembly.

indent += 1;
foreach (Type t in b.GetExportedTypes())
{
Display(0, "");
Display(indent, "Type: {0}", t);

// For each type, show its members & their custom attributes.

indent += 1;
foreach (MemberInfo mi in t.GetMembers())
{
Display(indent, "Member: {0}", mi.Name);
DisplayAttributes(indent, mi);

// If the member is a method, display information about its parameters.

if (mi.MemberType == MemberTypes.Method)
{
foreach (ParameterInfo pi in ((MethodInfo)mi).GetParameters())
{
Display(indent + 1, "Parameter: Type={0}, Name={1}", pi.ParameterType, pi.Name);
}
}

// If the member is a property, display information about the property's accessor methods.
if (mi.MemberType == MemberTypes.Property)
{
foreach (MethodInfo am in ((PropertyInfo)mi).GetAccessors())
{
Display(indent + 1, "Accessor method: {0}", am);
}
}
}
indent -= 1;
}
indent -= 1;
}
}

/// <summary>
/// Displays the custom attributes applied to the specified member.
/// </summary>
/// <param name="indent"></param>
/// <param name="mi"></param>
public static void DisplayAttributes(Int32 indent, MemberInfo mi)
{
// Get the set of custom attributes; if none exist, just return.
object[] attrs = mi.GetCustomAttributes(false);
if (attrs.Length == 0) { return; }

// Display the custom attributes applied to this member.
Display(indent + 1, "Attributes:");
foreach (object o in attrs)
{
Display(indent + 2, "{0}", o.ToString());
}
}
/// <summary>
/// Display a formatted string indented by the specified amount.
/// </summary>
/// <param name="indent"></param>
/// <param name="format"></param>
/// <param name="param"></param>
public static void Display(Int32 indent, string format, params object[] param)
{
string st = new string(' ', indent * 2);
MessageBox.Show(st);
string s=string.Format("format:{0},param:{1}.",format, param);
MessageBox.Show(s);
}
/// <summary>
///
/// </summary>
/// <param name="sender"></param>
/// <param name="e"></param>
private void button6_Click(object sender, EventArgs e)
{
// System.Reflection.MemberTypes
//4.6,4.5 .net
//TypeInfo t = typeof(Calendar).GetTypeInfo();
//4.6,4.5
// IEnumerable<PropertyInfo> pList = t.DeclaredProperties;
//4.5,4.6
//IEnumerable<MethodInfo> mList = t.DeclaredMethods;

//4.0
IEnumerable<PropertyInfo> pList = typeof(Calendar).GetProperties();
IEnumerable<MethodInfo> mList = typeof(Calendar).GetMethods();
IEnumerable<FieldInfo> fList = typeof(Calendar).GetFields();

StringBuilder sb = new StringBuilder();
sb.Append("Properties:");
foreach (PropertyInfo p in pList)
{

sb.Append("\n" + p.DeclaringType.Name + ": " + p.Name);
}
sb.Append("\nMethods:");
foreach (MethodInfo m in mList)
{
sb.Append("\n" + m.DeclaringType.Name + ": " + m.Name);
}
MessageBox.Show(sb.ToString());
}