# Double.CompareTo Method (Double)

**Silverlight**

Compares this instance to a specified double-precision floating-point number and returns an integer that indicates whether the value of this instance is less than, equal to, or greater than the value of the specified double-precision floating-point number.

**Namespace:**System

**Assembly:**mscorlib (in mscorlib.dll)

#### Parameters

- value
- Type: System.Double

A double-precision floating-point number to compare.

#### Return Value

Type: System.Int32A signed number indicating the relative values of this instance and value.

Return Value | Description |
---|---|

Less than zero | This instance is less than value. -or- This instance is not a number (NaN) and value is a number. |

Zero | This instance is equal to value. -or- Both this instance and value are not a number (NaN), PositiveInfinity, or NegativeInfinity. |

Greater than zero | This instance is greater than value. -or- This instance is a number and value is not a number (NaN). |

#### Implements

IComparable(Of T).CompareTo(T)This method implements the System.IComparable(Of T) interface and performs slightly better than the Double.CompareTo method because it does not have to convert the value parameter to an object.

Note that, although an object whose value is NaN is not considered equal to another object whose value is NaN (even itself), the IComparable(Of T) interface requires that A.CompareTo(A) return zero.

### Widening Conversions

Depending on your programming language, it might be possible to code a CompareTo method where the parameter type has fewer bits (is narrower) than the instance type. This is possible because some programming languages perform an implicit widening conversion that represents the parameter as a type with as many bits as the instance.

For example, suppose the instance type is Double and the parameter type is Int32. The Microsoft C# compiler generates instructions to represent the value of the parameter as a Double object, then generates a Double.CompareTo(Double) method that compares the values of the instance and the widened representation of the parameter.

Consult your programming language's documentation to determine if its compiler performs implicit widening conversions of numeric types. For more information, see the Type Conversion Tables topic.

### Precision in Comparisons

The precision of floating-point numbers beyond the documented precision is specific to the implementation and version of the .NET Framework. Consequently, a comparison of two particular numbers might change between versions of the .NET Framework because the precision of the numbers' internal representation might change.

The following example demonstrates generic and nongeneric versions of the CompareTo method for several value and reference types.

' This example demonstrates the generic and non-generic versions of the ' CompareTo method for several base types. ' The non-generic version takes a parameter of type Object, while the generic ' version takes a type-specific parameter, such as Boolean, Int32, or Double. Class Example Public Shared Sub Demo(ByVal outputBlock As System.Windows.Controls.TextBlock) Dim nl As String = vbCrLf Dim msg As String = _ "{0}The following is the result of using the generic and non-generic{0}" & _ "versions of the CompareTo method for several base types:{0}" Dim now As DateTime = DateTime.Now ' Time span = 11 days, 22 hours, 33 minutes, 44 seconds Dim tsX As New TimeSpan(11, 22, 33, 44) ' Version = 1.2.333.4 Dim versX As New Version("1.2.333.4") ' Guid = CA761232-ED42-11CE-BACD-00AA0057B223 Dim guidX As New Guid("{CA761232-ED42-11CE-BACD-00AA0057B223}") Dim a1 As [Boolean] = True, a2 As [Boolean] = True Dim b1 As [Byte] = 1, b2 As [Byte] = 1 Dim c1 As Int16 = -2, c2 As Int16 = 2 Dim d1 As Int32 = 3, d2 As Int32 = 3 Dim e1 As Int64 = 4, e2 As Int64 = -4 Dim f1 As [Decimal] = -5.5D, f2 As [Decimal] = 5.5D Dim g1 As [Single] = 6.6F, g2 As [Single] = 6.6F Dim h1 As [Double] = 7.7, h2 As [Double] = -7.7 Dim i1 As [Char] = "A"c, i2 As [Char] = "A"c Dim j1 As String = "abc", j2 As String = "abc" Dim k1 As DateTime = now, k2 As DateTime = now Dim l1 As TimeSpan = tsX, l2 As TimeSpan = tsX Dim m1 As Version = versX, m2 As New Version("2.0") Dim n1 As Guid = guidX, n2 As Guid = guidX ' The following types are not CLS-compliant. ' SByte, UInt16, UInt32, UInt64 outputBlock.Text &= String.Format(msg, nl) & vbCrLf Try ' The second and third Show method call parameters are automatically boxed because ' the second and third Show method declaration arguments expect type Object. Show(outputBlock, "Boolean: ", a1, a2, a1.CompareTo(a2), a1.CompareTo(CObj(a2))) Show(outputBlock, "Byte: ", b1, b2, b1.CompareTo(b2), b1.CompareTo(CObj(b2))) Show(outputBlock, "Int16: ", c1, c2, c1.CompareTo(c2), c1.CompareTo(CObj(c2))) Show(outputBlock, "Int32: ", d1, d2, d1.CompareTo(d2), d1.CompareTo(CObj(d2))) Show(outputBlock, "Int64: ", e1, e2, e1.CompareTo(e2), e1.CompareTo(CObj(e2))) Show(outputBlock, "Decimal: ", f1, f2, f1.CompareTo(f2), f1.CompareTo(CObj(f2))) Show(outputBlock, "Single: ", g1, g2, g1.CompareTo(g2), g1.CompareTo(CObj(g2))) Show(outputBlock, "Double: ", h1, h2, h1.CompareTo(h2), h1.CompareTo(CObj(h2))) Show(outputBlock, "Char: ", i1, i2, i1.CompareTo(i2), i1.CompareTo(CObj(i2))) Show(outputBlock, "String: ", j1, j2, j1.CompareTo(j2), j1.CompareTo(CObj(j2))) Show(outputBlock, "DateTime: ", k1, k2, k1.CompareTo(k2), k1.CompareTo(CObj(k2))) Show(outputBlock, "TimeSpan: ", l1, l2, l1.CompareTo(l2), l1.CompareTo(CObj(l2))) Show(outputBlock, "Version: ", m1, m2, m1.CompareTo(m2), m1.CompareTo(CObj(m2))) Show(outputBlock, "Guid: ", n1, n2, n1.CompareTo(n2), n1.CompareTo(CObj(n2))) ' outputBlock.Text &= String.Format("{0}The following types are not CLS-compliant:", nl) & vbCrLf outputBlock.Text &= String.Format("SByte, UInt16, UInt32, UInt64") & vbCrLf Catch e As Exception outputBlock.Text &= e.GetType().Name & vbCrLf End Try End Sub 'Main Public Shared Sub Show(ByVal outputBlock As System.Windows.Controls.TextBlock, ByVal caption As String, ByVal var1 As [Object], ByVal var2 As [Object], _ ByVal resultGeneric As Integer, ByVal resultNonGeneric As Integer) Dim relation As String outputBlock.Text &= caption If resultGeneric = resultNonGeneric Then If resultGeneric < 0 Then relation = "less than" ElseIf resultGeneric > 0 Then relation = "greater than" Else relation = "equal to" End If outputBlock.Text &= String.Format("{0} is {1} {2}", var1, relation, var2) & vbCrLf ' The following condition will never occur because the generic and non-generic ' CompareTo methods are equivalent. Else outputBlock.Text &= String.Format("Generic CompareTo = {0}; non-generic CompareTo = {1}", _ resultGeneric, resultNonGeneric) & vbCrLf End If End Sub 'Show End Class 'Sample ' 'This example produces the following results: ' 'The following is the result of using the generic and non-generic versions of the 'CompareTo method for several base types: ' 'Boolean: True is equal to True 'Byte: 1 is equal to 1 'Int16: -2 is less than 2 'Int32: 3 is equal to 3 'Int64: 4 is greater than -4 'Decimal: -5.5 is less than 5.5 'Single: 6.6 is equal to 6.6 'Double: 7.7 is greater than -7.7 'Char: A is equal to A 'String: abc is equal to abc 'DateTime: 12/1/2003 5:37:46 PM is equal to 12/1/2003 5:37:46 PM 'TimeSpan: 11.22:33:44 is equal to 11.22:33:44 'Version: 1.2.333.4 is less than 2.0 'Guid: ca761232-ed42-11ce-bacd-00aa0057b223 is equal to ca761232-ed42-11ce-bacd-00 'aa0057b223 ' 'The following types are not CLS-compliant: 'SByte, UInt16, UInt32, UInt64 '

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