public System.Int32 CompareTo(System.Object value)

Returns the sort order of the current instance compared to the specified System.Object .

Parameter value: The System.Object to compare to the current instance.

Returns: A System.Int32 containing a value that reflects the sort order of the current instance as compared to value. The following table defines the conditions under which the returned value is a negative number, zero, or a positive number.

Throws: : value is not a null reference and is not of type System.Double.

This method is implemented to support the System.IComparable interface. Note that, although a NaN is not considered to be equal to another NaN (even itself), the System.IComparable interface requires that A.CompareTo (A) return zero.

public System.Boolean Equals(System.Object obj)

Determines whether the current instance and the specified System.Object represent the same type and value.

Parameter obj: The System.Object to compare to the current instance.

Returns: true if obj is a System.Double with the same value as the current instance, otherwise false. If obj is a null reference or is not an instance of System.Double, returns false. If either obj or the current instance is a NaN and the other is not, returns false. If obj and the current instance are both NaN, positive infinity, or negative infinity, returns true.

This method overrides System.Object.Equals(System.Object).

public System.Int32 GetHashCode()

Generates a hash code for the current instance.

Returns: A System.Int32 containing the hash code for this instance.

The algorithm used to generate the hash code is unspecified. This method overrides System.Object.GetHashCode.

public static System.Boolean IsInfinity(System.Double d)

Determines whether the specified System.Double represents an infinity, which can be either positive or negative.

Parameter d: The System.Double to be checked.

Returns: true if d represents a positive or negative infinity value; otherwise false.

Floating-point operations return positive or negative infinity values to signal an overflow condition.

public static System.Boolean IsNaN(System.Double d)

Determines whether the value of the specified System.Double is undefined (Not-a-Number).

Parameter d: The System.Double to be checked.

Returns: true if d represents a NaN value; otherwise false.

Floating-point operations return NaN values to signal that the result of the operation is undefined. For example, dividing (Double) 0.0 by 0.0 results in a NaN value.

public static System.Boolean IsNegativeInfinity(System.Double d)

Determines whether the specified System.Double represents a negative infinity value.

Parameter d: The System.Double to be checked.

Returns: true if d represents a negative infinity value; otherwise false .

Floating-point operations return negative infinity values to signal an overflow condition.

public static System.Boolean IsPositiveInfinity(System.Double d)

Determines whether the specified System.Double represents a positive infinity value.

Parameter d: The System.Double to be checked.

Returns: true if d represents a positive infinity value; otherwise false.

Floating-point operations return positive infinity values to signal an overflow condition.

public static System.Double Parse(System.String s)

Returns the specified System.String converted to a System.Double value.

Parameter s: A System.String containing the value to convert. The string is interpreted using the System.Globalization.NumberStyles.Float and/or System.Globalization.NumberStyles.AllowThousands style.

Returns: The System.Double value obtained from s. If the parsed value is less than System.Double.MinValue, this method returns System.Double.NegativeInfinity . If the parsed value is greater than System.Double.MaxValue, this method returns System.Double.PositiveInfinity . If s equals System.Globalization.NumberFormatInfo.NaNSymbol, this method returns System.Double.NaN .

Throws: : s is a null reference.

Throws: : s is not in the correct style.

This version of System.Double.Parse(System.String) is equivalent to System.Double.Parse(System.String) (s, System.Globalization.NumberStyles.Float| System.Globalization.NumberStyles.AllowThousands , null ). The string s is parsed using the formatting information in a System.Globalization.NumberFormatInfo initialized for the current system culture. For more information, see System.Globalization.NumberFormatInfo.CurrentInfo .

public static System.Double Parse(System.String s, System.Globalization.NumberStyles style)

Returns the specified System.String converted to a System.Double value.

Parameter s: A System.String containing the value to convert. The string is interpreted using the style specified by style .

Parameter style: Zero or more System.Globalization.NumberStyles values that specify the style of s. Specify multiple values for style using the bitwise OR operator. If style is a null reference, the string is interpreted using the System.Globalization.NumberStyles.Float and System.Globalization.NumberStyles.AllowThousands styles.

Returns: The System.Double value obtained from s. If the parsed value is less than System.Double.MinValue, this method returns System.Double.NegativeInfinity . If the parsed value is greater than System.Double.MaxValue, this method returns System.Double.PositiveInfinity . If s equals System.Globalization.NumberFormatInfo.NaNSymbol, this method returns System.Double.NaN .

Throws: : s is a null reference.

Throws: : s is not in the correct style.

This version of System.Double.Parse(System.String) is equivalent to System.Double.Parse(System.String) (s, style, null ). The string s is parsed using the formatting information in a System.Globalization.NumberFormatInfo initialized for the current system culture. For more information, see System.Globalization.NumberFormatInfo.CurrentInfo .

public static System.Double Parse(System.String s, System.IFormatProvider provider)

Returns the specified System.String converted to a System.Double value.

Parameter s: A System.String containing the value to convert. The string is interpreted using the System.Globalization.NumberStyles.Float and/or System.Globalization.NumberStyles.AllowThousands style.

Parameter provider: A System.IFormatProvider that supplies a System.Globalization.NumberFormatInfo containing culture-specific formatting information about s.

Returns: The System.Double value obtained from s. If the parsed value is less than System.Double.MinValue, this method returns System.Double.NegativeInfinity . If the parsed value is greater than System.Double.MaxValue, this method returns System.Double.PositiveInfinity . If s equals System.Globalization.NumberFormatInfo.NaNSymbol, this method returns System.Double.NaN .

Throws: : s is a null reference.

Throws: : s is not in the correct style.

This version of System.Double.Parse(System.String) is equivalent to System.Double.Parse(System.String)(s, System.Globalization.NumberStyles.Float| System.Globalization.NumberStyles.AllowThousands , provider). The string s is parsed using the culture-specific formatting information from the System.Globalization.NumberFormatInfo instance supplied by provider. If provider is null or a System.Globalization.NumberFormatInfo cannot be obtained from provider , the formatting information for the current system culture is used.

public static System.Double Parse(System.String s, System.Globalization.NumberStyles style, System.IFormatProvider provider)

Returns the specified System.String converted to a System.Double value.

Parameter s: A System.String containing the value to convert. The string is interpreted using the style specified by style .

Parameter style: Zero or more System.Globalization.NumberStyles values that specify the style of s. Specify multiple values for style using the bitwise OR operator. If style is a null reference, the string is interpreted using the System.Globalization.NumberStyles.Float and System.Globalization.NumberStyles.AllowThousands styles.

Parameter provider: A System.IFormatProvider that supplies a System.Globalization.NumberFormatInfo containing culture-specific formatting information about s.

Returns: The System.Double value obtained from s. If the parsed value is less than System.Double.MinValue, this method returns System.Double.NegativeInfinity . If the parsed value is greater than System.Double.MaxValue, this method returns System.Double.PositiveInfinity . If s equals System.Globalization.NumberFormatInfo.NaNSymbol, this method returns System.Double.NaN .

Throws: : s is a null reference

Throws: : s is not in the correct style.

The string s is parsed using the culture-specific formatting information from the System.Globalization.NumberFormatInfo instance supplied by provider. If provider is null or a System.Globalization.NumberFormatInfo cannot be obtained from provider, the formatting information for the current system culture is used.

public System.String ToString(System.String format, System.IFormatProvider provider)

Returns a System.String representation of the value of the current instance.

Parameter format: A System.String containing a character that specifies the format of the returned string, optionally followed by a non-negative integer that specifies the precision of the number in the returned System.String .

Parameter provider: A System.IFormatProvider that supplies a System.Globalization.NumberFormatInfo instance containing culture-specific formatting information.

Returns: A System.String representation of the current instance formatted as specified by format. The string takes into account the information in the System.Globalization.NumberFormatInfo instance supplied by provider.

Throws: : format is invalid.

If provider is null or a System.Globalization.NumberFormatInfo cannot be obtained from provider , the formatting information for the current system culture is used. If format is a null reference, the general format specifier "G" is used. The following table lists the format characters that are valid for the System.Double type. For a detailed description of formatting, see the System.IFormattable interface. This method is implemented to support the System.IFormattable interface.

public System.String ToString(System.IFormatProvider provider)

Returns a System.String representation of the value of the current instance.

Parameter provider: A System.IFormatProvider that supplies a System.Globalization.NumberFormatInfo containing culture-specific formatting information.

Returns: A System.String representation of the current instance formatted using the general format specifier, ("G"). The string takes into account the formatting information in the System.Globalization.NumberFormatInfo instance supplied by provider.

This version of System.Double.ToString is equivalent to System.Double.ToString (null , provider ). If provider is null or a System.Globalization.NumberFormatInfo cannot be obtained from provider, the formatting information for the current system culture is used. The general format specifier formats the number in either fixed-point or exponential notation form. For a detailed description of the general format, see the System.IFormattable interface.

public System.String ToString()

Returns a System.String representation of the value of the current instance.

Returns: A System.String representation of the current instance formatted using the general format specifier, ("G"). The string takes into account the current system culture.

This version of System.Double.ToString is equivalent to System.Double.ToString (null, null ). The general format specifier formats the number in either fixed-point or exponential notation form. For a detailed description of the general format, see the System.IFormattable interface. This method overrides System.Object.ToString.

public System.String ToString(System.String format)

Returns a System.String representation of the value of the current instance.

Parameter format: A System.String that specifies the format of the returned string. For a list of valid values, see System.Double.ToString (System.String, System.IFormatProvider ).

Returns: A System.String representation of the current instance formatted as specified by format. The string takes into account the current system culture.

Throws: : format is invalid.

This version of System.Double.ToString is equivalent to System.Double.ToString (format, null ). If format is a null reference, the general format specifier "G" is used.

using System;
class test {
  public static void Main() {
    double d = 1234.56789;
    Console.WriteLine(d);
    string[] fmts = {"C","E","e5","F","G","N","P","R"};
    for (int i=0;i<fmts.Length;i++)
      Console.WriteLine("{0}: {1}", 
      fmts[i],d.ToString(fmts[i]));
  }
}
   

public System.Boolean Equals(System.Object obj)

Determines whether the current instance and a specified System.Object represent the same value.

Parameter obj: The System.Object to compare the current instance to.

Returns: true if obj and the current instance are of the same type and represent the same value; otherwise, false.

This method overrides System.Object.Equals(System.Object) .

public System.Int32 GetHashCode()

Generates a hash code for the current instance.

Returns: A System.Int32 containing the hash code for the current instance.

The algorithm used to generate the hash code is unspecified. This method overrides System.Object.GetHashCode .

public System.String ToString()

Returns a System.String representation of the fully-qualified name of the type of the current instance.

Returns: A System.String representation of the fully-qualified name of the type of the current instance.

This method overrides System.Object.ToString. This method returns the System.Type.FullName property.

public virtual System.Boolean Equals(System.Object obj)

Determines whether the specified System.Object is equal to the current instance.

Parameter obj: The System.Object to compare with the current instance.

Returns: true if obj is equal to the current instance; otherwise, false.

The statements listed below are required to be true for all implementations of the System.Object.Equals(System.Object) method. In the list, x, y, and z represent non-null object references. See System.Object.GetHashCode for additional required behaviors pertaining to the System.Object.Equals(System.Object) method. Implementations of System.Object.Equals(System.Object) should not throw exceptions. The System.Object.Equals(System.Object) method tests for referential equality , which means that System.Object.Equals(System.Object) returns true if the specified instance of Object and the current instance are the same instance; otherwise, it returns false . An implementation of the System.Object.Equals(System.Object) method is shown in the following C# code: public virtual bool Equals(Object obj) { return this == obj; } For some kinds of objects, it is desirable to have System.Object.Equals(System.Object) test for value equality instead of referential equality. Such implementations of Equals return true if the two objects have the same "value", even if they are not the same instance. The definition of what constitutes an object's "value" is up to the implementer of the type, but it is typically some or all of the data stored in the instance variables of the object. For example, the value of a System.String is based on the characters of the string; the Equals method of the System.String class returns true for any two string instances that contain exactly the same characters in the same order. When the Equals method of a base class provides value equality, an override of Equals in a class derived from that base class should invoke the inherited implementation of Equals . It is recommended (but not required) that types overriding System.Object.Equals(System.Object) also override System.Object.GetHashCode. Hashtables cannot be relied on to work correctly if this recommendation is not followed. If your programming language supports operator overloading, and if you choose to overload the equality operator for a given type, that type should override the Equals method. Such implementations of the Equals method should return the same results as the equality operator. Following this guideline will help ensure that class library code using Equals (such as System.Collections.ArrayList and System.Collections.Hashtable ) behaves in a manner that is consistent with the way the equality operator is used by application code. If you are implementing a value type, you should follow these guidelines: For reference types, the guidelines are as follows: If you implement System.IComparable on a given type, you should override Equals on that type. The System.Object.Equals(System.Object) method is called by methods in collections classes that perform search operations, including the System.Array.IndexOf(System.Array,System.Object) method and the System.Collections.ArrayList.Contains(System.Object) method.

using System;
class MyClass {
   static void Main() {
      Object obj1 = new Object();
      Object obj2 = new Object();
      Console.WriteLine(obj1.Equals(obj2));
      obj1 = obj2; 
      Console.WriteLine(obj1.Equals(obj2)); 
   }
}

using System;
public class Point: object {
 int x, y;
 public override bool Equals(Object obj) {
 //Check for null and compare run-time types.
 if (obj == null || GetType() != obj.GetType()) return false;
 Point p = (Point)obj;
 return (x == p.x) && (y == p.y);
 }
 public override int GetHashCode() {
 return x ^ y;
 }
}

class Point3D: Point {
 int z;
 public override bool Equals(Object obj) {
 return base.Equals(obj) && z == ((Point3D)obj).z;
 }
 public override int GetHashCode() {
 return base.GetHashCode() ^ z;
 }
}

using System;
class Rectangle {
 Point a, b;
 public override bool Equals(Object obj) {
 if (obj == null || GetType() != obj.GetType()) return false;
 Rectangle r = (Rectangle)obj;
 //Use Equals to compare instance variables
 return a.Equals(r.a) && b.Equals(r.b);
 }
 public override int GetHashCode() {
 return a.GetHashCode() ^ b.GetHashCode();
 }
}

using System;
public struct Complex {
 double re, im;
 public override bool Equals(Object obj) {
 return obj is Complex && this == (Complex)obj;
 }
 public override int GetHashCode() {
 return re.GetHashCode() ^ im.GetHashCode();
 }
 public static bool operator ==(Complex x, Complex y) {
 return x.re == y.re && x.im == y.im;
 }
 public static bool operator !=(Complex x, Complex y) {
 return !(x == y);
 }
}

public static System.Boolean Equals(System.Object objA, System.Object objB)

Determines whether two object references are equal.

Parameter objA: First object to compare.

Parameter objB: Second object to compare.

Returns: true if one or more of the following statements is true: otherwise returns false.

This static method checks for null references before it calls objA.Equals(objB ) and returns false if either objA or objB is null. If the Equals(object obj) implementation throws an exception, this method throws an exception.

using System;

public class MyClass {
   public static void Main() {
   string s1 = "Tom";
   string s2 = "Carol";
   Console.WriteLine("Object.Equals(\"{0}\", \"{1}\") => {2}", 
      s1, s2, Object.Equals(s1, s2));

   s1 = "Tom";
   s2 = "Tom";
   Console.WriteLine("Object.Equals(\"{0}\", \"{1}\") => {2}", 
      s1, s2, Object.Equals(s1, s2));

   s1 = null;
   s2 = "Tom";
   Console.WriteLine("Object.Equals(null, \"{1}\") => {2}",
       s1, s2, Object.Equals(s1, s2));

   s1 = "Carol";
   s2 = null;
   Console.WriteLine("Object.Equals(\"{0}\", null) => {2}", 
       s1, s2, Object.Equals(s1, s2));

   s1 = null;
   s2 = null;
   Console.WriteLine("Object.Equals(null, null) => {2}", 
       s1, s2, Object.Equals(s1, s2));
   }
}
   

public System.Void Finalize()

Allows a System.Object to perform cleanup operations before the memory allocated for the System.Object is automatically reclaimed.

During execution, System.Object.Finalize is automatically called after an object becomes inaccessible, unless the object has been exempted from finalization by a call to System.GC.SuppressFinalize(System.Object). During shutdown of an application domain, System.Object.Finalize is automatically called on objects that are not exempt from finalization, even those that are still accessible. System.Object.Finalize is automatically called only once on a given instance, unless the object is re-registered using a mechanism such as System.GC.ReRegisterForFinalize(System.Object) and System.GC.SuppressFinalize(System.Object) has not been subsequently called. Conforming implementations of the CLI are required to make every effort to ensure that for every object that has not been exempted from finalization, the System.Object.Finalize method is called after the object becomes inaccessible. However, there may be some circumstances under which Finalize is not called. Conforming CLI implementations are required to explicitly specify the conditions under which Finalize is not guaranteed to be called. For example, Finalize might not be guaranteed to be called in the event of equipment failure, power failure, or other catastrophic system failures. In addition to System.GC.ReRegisterForFinalize(System.Object) and System.GC.SuppressFinalize(System.Object), conforming implementations of the CLI are allowed to provide other mechanisms that affect the behavior of System.Object.Finalize . Any mechanisms provided are required to be specified by the CLI implementation. The order in which the Finalize methods of two objects are run is unspecified, even if one object refers to the other. The thread on which Finalize is run is unspecified. Every implementation of System.Object.Finalize in a derived type is required to call its base type's implementation of Finalize . This is the only case in which application code calls System.Object.Finalize . The System.Object.Finalize implementation does nothing. A type should implement Finalize when it uses unmanaged resources such as file handles or database connections that must be released when the managed object that uses them is reclaimed. Because Finalize methods may be invoked in any order (including from multiple threads), synchronization may be necessary if the Finalize method may interact with other objects, whether accessible or not. Furthermore, since the order in which Finalize is called is unspecified, implementers of Finalize (or of destructors implemented through overriding Finalize) must take care to correctly handle references to other objects, as their Finalize method may already have been invoked. In general, referenced objects should not be considered valid during finalization. See the System.IDisposable interface for an alternate means of disposing of resources. For C# developers: Destructors are the C# mechanism for performing cleanup operations. Destructors provide appropriate safeguards, such as automatically calling the base type's destructor. In C# code, System.Object.Finalize cannot be called or overridden.

public virtual System.Int32 GetHashCode()

Generates a hash code for the current instance.

Returns: A System.Int32 containing the hash code for the current instance.

System.Object.GetHashCode serves as a hash function for a specific type. A hash function is used to quickly generate a number (a hash code) corresponding to the value of an object. Hash functions are used with hashtables. A good hash function algorithm rarely generates hash codes that collide. For more information about hash functions, see The Art of Computer Programming , Vol. 3, by Donald E. Knuth. All implementations of System.Object.GetHashCode are required to ensure that for any two object references x and y, if x.Equals(y) == true, then x.GetHashCode() == y.GetHashCode(). Hash codes generated by System.Object.GetHashCode need not be unique. Implementations of System.Object.GetHashCode are not permitted to throw exceptions. The System.Object.GetHashCode implementation attempts to produce a unique hash code for every object, but the hash codes generated by this method are not guaranteed to be unique. Therefore, System.Object.GetHashCode may generate the same hash code for two different instances. It is recommended (but not required) that types overriding System.Object.GetHashCode also override System.Object.Equals(System.Object) . Hashtables cannot be relied on to work correctly if this recommendation is not followed. Use this method to obtain the hash code of an object. Hash codes should not be persisted (i.e. in a database or file) as they are allowed to change from run to run.

using System;
public struct Int32 {
 int value;
 //other methods...

 public override int GetHashCode() {
 return value;
 }
}

using System;
public struct Point {
 int x;
 int y; 
 //other methods
 
 public override int GetHashCode() {
 return x ^ y;
 }
}

using System;
public class SomeType {
 public override int GetHashCode() {
 return 0;
 }
}

public class AnotherType {
 public override int GetHashCode() {
 return 1;
 }
}

public class LastType {
 public override int GetHashCode() {
 return 2;
 }
}
public class MyClass {
 SomeType a = new SomeType();
 AnotherType b = new AnotherType();
 LastType c = new LastType();

 public override int GetHashCode () {
 return a.GetHashCode() ^ b.GetHashCode() ^ c.GetHashCode();
 }
}

using System;
public struct Int64 {
 long value;
 //other methods...

 public override int GetHashCode() {
 return ((int)value ^ (int)(value >> 32));
 }
}

public System.Type GetType()

Gets the type of the current instance.

Returns: The instance of System.Type that represents the run-time type (the exact type) of the current instance.

For two objects x and y that have identical run-time types, System.Object.ReferenceEquals(System.Object,System.Object)(x.GetType(),y.GetType()) returns true .

using System;
public class MyBaseClass: Object {
}
public class MyDerivedClass: MyBaseClass {
}
public class Test {
   public static void Main() {
   MyBaseClass myBase = new MyBaseClass();
   MyDerivedClass myDerived = new MyDerivedClass();

   object o = myDerived;
   MyBaseClass b = myDerived;

   Console.WriteLine("mybase: Type is {0}", myBase.GetType());
   Console.WriteLine("myDerived: Type is {0}", myDerived.GetType());
   Console.WriteLine("object o = myDerived: Type is {0}", o.GetType());
   Console.WriteLine("MyBaseClass b = myDerived: Type is {0}", b.GetType());
   }
}

protected System.Object MemberwiseClone()

Creates a shallow copy of the current instance.

Returns: A shallow copy of the current instance. The run-time type (the exact type) of the returned object is the same as the run-time type of the object that was copied.

System.Object.MemberwiseClone creates a new instance of the same type as the current instance and then copies each of the object's non-static fields in a manner that depends on whether the field is a value type or a reference type. If the field is a value type, a bit-by-bit copy of all the field's bits is performed. If the field is a reference type, only the reference is copied. The algorithm for performing a shallow copy is as follows (in pseudo-code): for each instance field f in this instance if (f is a value type) bitwise copy the field if (f is a reference type) copy the reference end for loop This mechanism is referred to as a shallow copy because it copies rather than clones the non-static fields. Because System.Object.MemberwiseClone implements the above algorithm, for any object, a, the following statements are required to be true: System.Object.MemberwiseClone does not call any of the type's constructors. If System.Object.Equals(System.Object) has been overridden, a.MemberwiseClone().Equals(a) might return false . For an alternate copying mechanism, see System.ICloneable . System.Object.MemberwiseClone is protected (rather than public) to ensure that from verifiable code it is only possible to clone objects of the same class as the one performing the operation (or one of its subclasses). Although cloning an object does not directly open security holes, it does allow an object to be created without running any of its constructors. Since these constructors may establish important invariants, objects created by cloning may not have these invariants established, and this may lead to incorrect program behavior. For example, a constructor might add the new object to a linked list of all objects of this class, and cloning the object would not add the new object to that list -- thus operations that relied on the list to locate all instances would fail to notice the cloned object. By making the method protected, only objects of the same class (or a subclass) can produce a clone and implementers of those classes are (presumably) aware of the appropriate invariants and can arrange for them to be true without necessarily calling a constructor.

using System;
class MyBaseClass {
   public static string CompanyName = "My Company";
   public int age;
   public string name;
}

class MyDerivedClass: MyBaseClass {

   static void Main() {
   
   //Create an instance of MyDerivedClass
   //and assign values to its fields.
   MyDerivedClass m1 = new MyDerivedClass();
   m1.age = 42;
   m1.name = "Sam";

   //Do a shallow copy of m1
   //and assign it to m2.
   MyDerivedClass m2 = (MyDerivedClass) m1.MemberwiseClone();
   }
}

+---------------+

|     42        |                           m1 

+---------------+

|     +---------|-----------------> "Sam" 

+---------------+                    /|\ 

                                      | 

+---------------+                     | 

|     42        |                     |      m2 

+---------------+                     | 

|      +--------|---------------------| 

+---------------+

public static System.Boolean ReferenceEquals(System.Object objA, System.Object objB)

Determines whether two object references are identical.

Parameter objA: First object to compare.

Parameter objB: Second object to compare.

Returns: True if a and b refer to the same object or are both null references; otherwise, false.

This static method provides a way to compare two objects for reference equality. It does not call any user-defined code, including overrides of System.Object.Equals(System.Object) .

using System;
class MyClass {
   static void Main() {
   object o = null;
   object p = null;
   object q = new Object();
   Console.WriteLine(Object.ReferenceEquals(o, p));
   p = q;
   Console.WriteLine(Object.ReferenceEquals(p, q));
   Console.WriteLine(Object.ReferenceEquals(o, p));
   }
}
   

public virtual System.String ToString()

Creates and returns a System.String representation of the current instance.

Returns: A System.String representation of the current instance.

System.Object.ToString returns a string whose content is intended to be understood by humans. Where the object contains culture-sensitive data, the string representation returned by System.Object.ToString takes into account the current system culture. For example, for an instance of the System.Double class whose value is zero, the implementation of System.Double.ToString might return "0.00" or "0,00" depending on the current UI culture. Although there are no exact requirements for the format of the returned string, it should as much as possible reflect the value of the object as perceived by the user. System.Object.ToString is equivalent to calling System.Object.GetType to obtain the System.Type object for the current instance and then returning the result of calling the System.Object.ToString implementation for that type. The value returned includes the full name of the type. It is recommended, but not required, that System.Object.ToString be overridden in a derived class to return values that are meaningful for that type. For example, the base data types, such as System.Int32, implement System.Object.ToString so that it returns the string form of the value the object represents. Subclasses that require more control over the formatting of strings than System.Object.ToString provides should implement System.IFormattable, whose System.Object.ToString method uses the culture of the current thread.

using System;

class MyClass {
   static void Main() {
      object o = new object();
      Console.WriteLine (o.ToString());
   }
}
      

public System.Int32 CompareTo(System.Object obj)

Returns the sort order of the current instance compared to the specified object.

Parameter obj: The System.Object to compare to the current instance.

Returns: A System.Int32 containing a value that reflects the sort order of the current instance as compared to object. The following table defines the conditions under which the returned value is a negative number, zero, or a positive number.

For any objects A, B and C, the following are required to be true: A.CompareTo(A) is required to return zero. If A.CompareTo(B) returns zero then B.CompareTo(A) is required to return zero. If A.CompareTo(B) returns zero and B.CompareTo(C) returns zero then A.CompareTo(C) is required to return zero. If A.CompareTo(B) returns a value other than zero then B.CompareTo(A) is required to return a value of the opposite sign. If A.CompareTo(B) returns a value x not equal to zero, and B.CompareTo(C) returns a value y of the same sign as x, then A.CompareTo(C) is required to a value of the same sign as x and y . The exact behavior of this method is unspecified. The intent of this method is to provide a mechanism that orders instances of a class in a manner that is consistent with the mathematical definitions of the relational operators (<, >, and ==), without regard for class-specific definitions of the operators. Use the System.IComparable.CompareTo(System.Object) method to determine the ordering of instances of a class.

public System.String ToString(System.String format, System.IFormatProvider formatProvider)

Returns a System.String representation of the value of the current instance.

Parameter format: A System.String that specifies the format of the returned string. If format is a null reference or the empty string, the default format defined for the type of the current instance is used.

Parameter formatProvider: A System.IFormatProvider that supplies a formatting object containing culture-specific formatting information, or null .

Returns: A System.String containing the value of the current instance formatted in accordance with format and formatProvider .

Throws: : The specified format is invalid or cannot be used with the type of the current instance.

Conforming implementations do not throw an exception when format and/or formatProvider are null references. If formatProvider is a null reference, the string is constructed using a system-supplied formatting object containing information for the current system culture. If format is null, the string is constructed using a system-supplied default format appropriate for the type of the current instance. If the object returned by formatProvider supplies a culture-specific representation of symbols or patterns included in format, the returned string is required to use the information supplied by formatProvider . Implement to allow consumers of a class to use format strings and formatting objects to control the way in which the class is represented as a string.

using System;
class FormattableExample {
    public static void Main() {
    double d = 123.12345678901234;
    string[] formats = {"C","E","e","F","G","N","P","R"};
    for (int i = 0; i< formats.Length;i++) 
        Console.WriteLine("{0:R} as {1}:  {2}",d,formats[i],d.ToString(formats[i],null));

    string[]intFormats = {"D","x","X"};
    int val = 255;
    for (int i = 0; i< intFormats.Length;i++) 
        Console.WriteLine("{0} as {1}:  {2}",val,intFormats[i],val.ToString(intFormats[i],null));

    }
}